Prof. Yumi suffers from this. Though he does care for her, throughout the series he rather neglected Sayaka. It was obvious his family was less important to him than his career, and often he was absent when her daughter needed him. Likewise, his niece Yuri is a conceited, cranky brat, and he explains that it's because her parents never have time for her.
A bigger example is Kenzo Kabuto. He almost died in a laboratory experiment gone wrong, but his father saved his life. However both of them thought it would be better not telling Kouji and Shiro— Kenzo's sons— he had survived. For years Kouji and Shiro grew up mostly alone, thinking their father died alongside their mother while he was building a Humongous Mecha to defend humankind. When Kenzo revealed the truth to them, Kouji was too glad to hold a grudge, but Shiro took a long while until before he could forgive him. Also, Kenzo had no troubles slapping his adoptive son when he thought Tetsuya was crossing the line. All of it finally bit everyone's butts at the end of the series.
Another Mazinger Z character who suffered due to Abusive Parents was... Big Bad Dr. Hell himself. In the manga continuity penned by Gosaku Ota that gave a backstory to most of the villains, his mother abused him physically and emotionally (insulting him, stating openly she didn't want kids and she would be better off if he had never been born...) as his father shrugged it off indifferently. The physical and psychological mistreatment he suffered back then is one of the reasons he decided Humans Are Bastards and became so unhinged.
It happened several times, not only to Kouji but also to Sayaka. One example of it was original manga's episode 8 when they saw each other naked in the hot springs. Curiously there was no slapping or reproaching. After the initial screams they calmed down and apologized at each other. It was even cute.
And in the Mazinger vs Great General of Darkness movie, Kouji accidentally walked in Sayaka when she was having a shower in one of the first scenes. This time he was slapped.
Ace Pilot: In the trilogy, Kouji (like Duke Fleed) had to grow into the role. In the first chapters it was painfully obvious than he had no idea how to pilot a war vehicle; nevertheless, through training and battles he became a true ace. In contrast, Tetsuya Tsurugi was trained into it before the series and is the Trope Codifier (and Deconstruction) of the Hot-BloodedAce Pilot in Humongous Mecha anime.
Action Girl: Sayaka was among the first action-geared ladies in Japanese anime
Achilles in His Tent: Kouji, of all people, did this in episode 7. After mobs of people expressed their displeasure in having their hometown leveled by a Humongous Mecha battle by harassing him, and after a quarrel with Sayaka, Kouji decided since nobody wanted him fighting, he would stay at home. Of course, it did not last long.
Action-Hogging Opening: The openings of the trilogy feature more action (featuring the titular HumongousMecha tearing its way through an army of enemies), and a better animation than an average episode of their series, especially Grendizer's.
Adults Are Useless: The series plays with the trope, but subverts it. The most powerful weapon in the world is handed over to a teenager, and Dr. Hell and his servants (who are all adults) are unable to defeat a bunch of teenagers... but neither Kouji nor Sayaka nor Shiro (nor Boss and his gang) would have been capable of protecting humankind and defeating Dr. Hell if they had not been supported by plenty of adults. All workers in the Institute (starting with Prof. Yumi, who was a good scientist and strategist) were fully competent and without them Mazinger Z would not have gotten the frequent upgrades, repairs and maintenance it needed.
Advanced Ancient Acropolis: The Mykene inhabited the Greek island of Bardos. Their technological level was miles ahead of any other culture of the same time, and the rest of the world would need millennia to catch up. However, one earthquake shook their island and destroyed their cities, and they were forced to seek shelter underground. They founded another civilization Beneath the Earth, but on the surface the only remainder left of their presence were abandoned, decaying ruins, and old legends about the Humongous Mecha they used to defend their land.
Air Jousting: Dr. Hell started sending flying Beasts after Kouji and Mazinger-Z as soon as episode 19. Mazinger got a Mid-Season Upgrade to flight capability in episode 34, and in that same episode Kouji got his first aerial battle (against Genocyder F9). Since that moment and through the whole series he had many climatic aerial duels against flying enemies like Kirma K5 (who used hit-and-fly-off tactics) or Jeiser J1 (that could easily blast Mazinger away, was impervious to his weapons and forced Kouji to chase it across the sky despite Mazinger being nearly out of power with a damaged cockpit).
Airborne Aircraft Carrier: Ghoul, a flying fortress commanded by Count Brocken. It had the capability to house a large number of Brocken's Iron Cross troops, dozens of combat jets and Mechanical Beasts, and it could mask itself from radar devices, fly at high altitude and spend several months airborne without needing to land.
All Myths Are True: Dr. Hell joined an archaelogical expedition to the Greek island of Bardos, thinking maybe several ancient legends that told the island was defended by an army of mechanical giants were true. Unfortunately for everybody else, he was right. Classical Mythology plays an increasingly important role in each retelling of the series, until the point where Greek gods start showing up and Great MazingerBig Bad is revealed to be Hades in Shin Mazinger.
All There in the Manual: Many supplementary materials (such like the Mazinbible book) have been released, providing with additional information and backstory about the series and the worlds where they happen, their characters, blueprints of mechas and bases...
In Great Mazinger, the final battle is won when Mazinger, Great Mazinger, Aphrodite A and Venus A combine their strongest attacks to bring Cool Airship Demonika down.
In UFO Robo Grendizer, Mazinger-Z, Great Mazinger and Grendizer combined all of their attacks in one manga scene to destroy a Vegan starship. And in one of the movies, Grendizer and Great Mazinger combined their Chest Blaster attacks to destroy a Saucer Beast.
In the first episode of Mazinkaiser, Mazinger-Z and Great Mazinger used their Chest Blaster weapons in combination to melt a Mechanical Beast to slag.
Great Mazinger and Getter Robo have also combined their attacks in several movies.
Almost Kiss: Kouji and Sayaka do this in the Mazinger-Z vs Great General of Darkness, right when Kouji is going to sortie with Mazinger-Z to fight a battle he knows he can not win, and thinking he'll die. Sayaka stops him to give him his little brother's birthday gift, and both stare into each other's eyes for a long while... and then Kouji turns around and leaves. Cue millions of fans groaning in exasperation. In the the manga though, they do kiss.
Alternate Continuity: There are several manga versions. The original one was written and drawn by Go Nagai. A second version was drawn by Gosaku Ota — one of his assistants — that ran parallel to the anime series and was heavily influenced by it (That version was made when Sueisha realized two Mazinger Z mangas would make more profit that one). Gosaku Ota's manga showed the backstory of Dr. Hell and his underlings. Other versions are: New Mazinger, Mazin Saga, Mazinger Angels, Shin Mazinger, Shin Mazinger Zero, different one-shots and short stories — one of them made by Ishikawa)... And then you have the different anime versions...
Alternate Universe: There are a bunch of Mazinger-related series... and nearly each one of them is set in a different universe with alternate versions of the characters or with completely different characters and themes.
An Axe to Grind: A few Mechanical Beasts used axes. In the Mazinger vs Devilman film, the first Beast showed up used a double-headed, throwing axe. And in the Mazinger-Z vs Great General of Darkness film Juuma— one of the Co-Dragons of Ankoku Daishogun— wielded one (and nearly skewers Mazinger's head and Kouji with it).
Ancestral Weapon: Kouji probably counts, if you count his grandpa's and his dad'sgiant robot as an ancestral weapon.
And the Rest: It happened constantly. Often the villains told a sentence along the lines of "Go ahead! Finish with Mazinger-Z... and the other two robots!". The other two robots being Aphrodite-A (or Diana-A) and Boss Borot. Needless to say, it was intended to be demeaning.
And This Is For...: In the manga, as they are making preparations for the Final Battle, Kouji announces— loudly, of course— that, for his poor murdered granddad, for all people has been hurt, and for the peace of Japan... THIS TIME HE'LL DESTROY DR. HELL FOR GOOD!
Anything You Can Do, I Can Do Better: Prof. Kabuto was this to Dr. Hell. Hell had ALWAYS felt upstaged by Yuuzo Kabuto since they were in the same college and his rival was more popular, a bigger genius and was loved by the woman Hell was in love with. When Mazinger-Z destroyed his first Mechanical Beasts, Hell had a break-down because he knew Kabuto had managed to create a Humongous Mecha could beat anything he could build.
Applied Phlebotinum: Mazinger-Z is powered with Koushi Ryoku (Photon Atomic) energy. When it runs out, Mazinger ceases functioning. It was discovered by Dr. Kabuto (ironically, in the Gosaku Ota episodes, it was stated he was already investigating it back in college, and one of his classmates helped him by correcting his calculations. Name of that classmate? Hell). It is repeatedly stated and shown in the series Photon energy must be used in conjunction with a body made from Japanium, or the Humongous Mecha is less effective: either the weapons are too powerful and overload the computer and damage the armor, or the robot is sturdy but its weapons are weak.
Phlebotinum Battery: Mazinger Z runs on an engine powered by Photon Atomic energy. When it runs out of Photon energy, it ceases functioning and it has to be replenished to work again. Great Mazinger and Mazinkaiser also work with a Photon engine. Grendizer works with the same principle but with a completely different energy source.
Arc Words: "When you pilot Mazinger, you can become a god or a devil."
Arm Cannon: Besides shooting its fists, Mazinger Z hid a cannon in each upper arm shot drilling missiles. Several Mechanical Beasts had cannons (or even machine guns like Balkan P5) instead of limbs. A stands out example is Debira X1 (a beast seemed a blend between bat and vampire) had a hidden leg cannon (and blew one of Mazinger's arms off with it).
Armed Legs: Mazinger-Z had one rocket on each foot to propel it underwater, but Kouji also used them to fight. Usually he blast with them at a Mechanical Beast's face to force it to release Mazinger.
The series tried to avert this trope. Mazinger's cockpit offered little protection, and in the first chapters, Kouji repeatedly got hurt and even knocked out because he fought in civilian clothes (and in the manga the villains were aware of that and tried to exploit it. In an early story, Baron Ashura commanded a Mechanical Beast to grab Mazinger, fly high and drop it, knowing as Kouji did that the freefall's impact would kill the pilot, even if Mazinger endured it). In order to avoid that, he began wearing a Latex Space Suit made out of Super Alloy Z to protect his body during the fights. It was more protective than plain clothes, but he still got injured while wearing it.
On the other hand, New Mazinger averted this trope. Kabuto wore Power Armor that protected him efficiently during the whole story.
Armor-Piercing Attack: In episode 54 Mechanical Monster Jeiser J1's hide was too tough to be pierced by Mazinger-Z's weapons. In order to solve the problem, the Institute's scientists treated the Mazinger's fists with Photon Atomic energy radiation to harden them. Ïn the next fight Mazinger's Rocket Punch easily tore through the Jeiser's armor.
Attack! Attack! Attack!: Kouji falls into this sometimes, when he is facing a Mechanical Beast several times stronger than Mazinger and still he refuses retiring or playing defensive. However, he still is able to think strategically, come up with plans quickly, and every so often you can talk him into leaving the battlefield, so he is not the biggest offender in the series (that one would be Tetsuya).
In his battle against Jeiser J1 his enemy was too sturdy to be taken down easily, his mecha was quickly running out of power, the mechanisms were so strained that the controls were giving off sparks and the cockpit was filling with smoke, and he was risking to a freefall (since they were fighting in midair)... and still he refused going back to the Home Base, waiting for a chance to nail the Beast instead.
In the whole Mazinsaga the only method the army tries to stop the Robeasts is attacking them endlessly, and when it fails, send more troops in. They did get one success in the Gosaku Ota Mazinger-Z manga, though, but they needed a nuke to achieve it. You would think that after the first few times they would learn that Giant Equals Invincible.
Attack Its Weak Point: When a Mechanical Beast seemed too powerful Kouji, Sayaka, Prof. Yumi and the rest of the scientists of the Institute would examine footage of the battle to try to come up with a strategy or find a weak point. Good examples were Bikong O9 (its weak point were the horns jutting out of its head) or Jinray S1 (It was a Mechanical Beast that flew and struck at Match 5 speed. It beat Mazinger-Z and fled without Kouji even knowing what had hit him. However its weak point were the legs where its rockets were located. Kouji defeated it by destroying one of them).
Attack the Tail: In the Mazinger-Z vs Great General of Darkness feature, a serpent-like Robeast had one head on each end. The tinier head, located on the tip of the tail, was the REAL head (Mykene Warbeasts were controlled by grafting the head of a Mykene warrior into a Robeast), so when Kouji cut its tail off, the Warbeast lost control and it was destroyed.
Boom, Headshot: Baremos Q7 was a Mechanical Beast built with stolen samples of Alloy Z. However its head was made of a less sturdy metal since Dr. Hell did not have enough alloy Z. During the battle, Kouji eventually noticed the Robeast was ALWAYS protecting its head. Logically, he aimed for it. Another example happened in one of the first chapters, when he was told Bikong O9 weak point were its horns.
Go for the Eye: Gumbina M5's armor was completely impervious to Mazinger-Z's weapons. Kouji not even was capable of scratching or denting it. Its weak point were its large eyes located on the chest. Sayaka ended up the battle when Aphrodite-A's Torpedo Tits managed to hit them. Ouch.
In the "Mazinger-Z vs Great General of Darkness", Kouji was sword-dueling against a clearly superior Warbeast had pinned Mazinger-Z on the ground and was trying run its sword through it. Kouji shot Mazinger's drill missiles and managed hit one of its eyes. The Warbeast crumbled down due to the missiles boring into its head and exploding. Double ouch.
Ozones B3 subverted the trope. It had a huge, glowing, single eye on its head... but it was not its weak point, and Kouji did not try to destroy it.
Sayaka constantly demanded to be the center of attention. Justified because her father was Married to the Job so she tried to show him that she was capable of helping him, and no one valued her unless she proved her worth.
Her younger cousin Yuri was a cranky, loud, attention-seeking brat who wanted everyone to pay attention to her. It's also justified, since her parents were always too busy to look after her.
In episode 29 Kouji saw a Mechanical Beast— Grengus C3— walking from the direction where Aphrodite A— Sayaka's Fembot— had gone before. Inmediately he panicked, got on a bike and drove towards the place, yelling "Sayaka" all the way (he was so freaked out he did not realize the bike he had got was not his). When he finally found her— wounded and lying down on the floor beside Aphrodite A's remains— he shook her awake and hugged her.
And in another episode, Kouji and Sayaka got into an actually serious fight, and Sayaka refused to back him up in battle. When he was seriously injured, Sayaka took care of him in the hospital and kissed him in his comatose sleep.
Back Stab: In the Gosaku Ota manga continuity, Dragon with an Agenda Archduke Gorgon murdered Big Bad Dr. Hell by stabbing him from behind with one sword when he was distracted. Afterwards he pulled his sword from the body, said "So long, old madman" and left him lying -and bleeding- on the ground, laughing all the way as he left.
Bad Future: In Shin Mazinger Zero the world and the entire mankind have been burnt to ashes by a Mazinger-Z turned Eldritch Abomination in the future, and Minerva-X sends Kouji back in time to save everybody. However they are locked into a Groundhog Peggy Sue loop since Kouji has failed every time so far, and Minerva keeps sending him back because she can trust no one else. They have repeated the same cycle almost three thousand times when the series starts, so it seems not matter what Kouji does, the world is doomed. Given that Minerva is the original Minerva-X, future in the Mazinger Z universe seems bleak, indeed.
Bad Moon Rising: In Grendizer, the Moon becoming red was a sign the Alliance Vegan was getting ready for another attack; the main characters eventually learnt to watch for that. One of the manga versions penned by Gosaku Ota reinforced that: in the first pages a red skull appeared on the Moon's surface (a sign of the Vegans had come) and Duke felt upset when he saw it, and wondered if that was a bad omen.
Bad Santa: In episode 56, set during winter, Dr. Hell proved to be The Grinch when he unleashed a Mechanical Beast -Satan Claus P10- that resembled an evil Santa riding a jet-propelled sleigh, using a whip that fired missiles.
Badass Back: Hilariously subverted in the first chapter of Mazinger ZGo Nagai manga. Sayaka sortie in Aphrodite-A to stop a mysterious Humongous Mecha is trashing the city that mysterious Humongous Mecha being Mazinger-Z, "piloted" by a Kouji Kabuto had just got on the robot and had absolutely no idea of how controlling the damned thing. When she strikes it, the Humongous Mecha easily withstands its attack, heaves the Fem Bot, throws it away... and then it turns its back towards her. Sayaka is incensed, believing that the robot thinks Aphrodite is not good enough to fight and is making fun of her. Her father is worried and requests her being careful because it is dangerous even if it has its back turned to her. She gets ready to attack, when the Humongous Mecha suddenly turns around... and its pilot manages to communicate with her and explain he did all that because he did not know how to pilot the robot.
Badass Family: Dr. Kabuto and his son built the most powerful robots in the world. Kouji has fought and stomped whole squads of armed soldiers, and trashed dozens of massive war machines. Even his little brother is also perfectly capable of defending himself in a one on one fight.
Badass Arm-Fold: Kouji sometimes used the pose. A good example in an episode in which Mazinger-Z is nearly completely depleted from energy during a battle, the control deck is smoking and giving off sparks due to the strain, the weapons don't work, Prof. Yumi is demanding Kouji retreat because he'll die otherwise... and Kouji simply folds his arms across his chest as he calmly waits for one chance to blast the Beast down. Bad. Ass.
The Bait: Often Kouji voluntereed for the role. Sayaka, too. Boss could be more willing or more reluctant to play bait depending on the situation.
Baleful Polymorph: In a story of the Gosaku Ota episodes, the Chip Kamoy— a race of giant, man-eating, fishlike Humanoid Abominations from another dimension— tried to invade Earth. They kidnapped a normal human girl and transformed her into a mermaid-like being to communicate with humans. Later they trapped Kouji and she helped him to escape. In punishment she got executed by the Chip Kamoy.
Barbie Doll Anatomy: In the original anime, Kouji had some shirtless scenes, and nipples were nowhere to be seen.
Partially averted in Mazinkaiser: when Sayaka's top comes undone in the fourth episode, the nipples and areola are present and accounted for. Don't know where the male nipples are hiding, though.
Barehanded Blade Block: Kouji was forced to pull this maneouver sometimes. A specially awesome example happened in episode 52: he is fighting a Mechanical Beast armed with scythes can easily slice and dice his Humongous Mecha. During the fight the Beast tries to cleave Mazinger in half... and Mazinger blocks the scythe with both hands and splits it. And then he grabs his enemy's broken weapon, slices its remaining scythe off, and stabs the Robeast with its own weapon! Justified since the mecha can have its hands repaired.
Bash Brothers: Kouji and Boss (when they were not fighting), Kouji and Tetsuya (when they were not arguing) and Kouji and Duke.
Batman Gambit: Kouji used several throughout the whole trilogy, often mixing them with Crazy Enough to Work. For example, in one chapter a Mechanical Beast (Kirma K5) sliced a chunk of one Mazinger-Z's wing during an aerial battle. Kouji could not balance his Humongous Mecha and he fell towards the ground. Then he goaded Kirma into attacking him again, and positioned Mazinger so his foe's Sinister Scythe sliced a chunk of the another wing. Now the Mazinger wings were the same length again, and his enemy was nearby, he could balance Mazinger back and grab Kirma. As he was beating the crap out of the Robeast he gloated it should have let him drop.
Prof. Yumi -and later Prof. Kenzo Kabuto- also used the Batman Gambit fairly often.
Beam-O-War: Sometimes Mazinger Z and a Mechanical Beast engaged in this, and usually Kouji used Mazinger's Breast Fire to couterattack their energy beams or waves. Some examples happened in episode 11 (against Brighton J2) and episode 30 (against Brutus M3).
Becoming the Mask: Erika. An android built by Dr. Hell that suffered from amnesia and had forgotten her origins. She genuinely believed she was a normal girl, and when she was told her true nature, she rejected it. In the end she helped Kouji and died doing so.
Beehive Barrier: The Photonic Research Institute uses a energy barrier to protect the facility when under attack.
Beneath the Earth: Not surprisingly, Mazinger Z introduced this trope in Humongous Mecha anime. The Mykene were a civilization lived and thrived in the Greek island of Bardos millennia ago, using mechanical giantsblast fire from their chests to protecting their land from invaders. An earthquake destroyed their island and forced them to seek shelter underground. They lived below Earth for millennia, building their cities in networks of subterranean tunnels and caverns and grafting their bodies into Humongous Mecha to survive.
Berserk Button: Kouji has several of them: insulting his grandfather, hurting Sayaka, harming innocents... Sayaka also gets easily mad when someone mocks her skills or makes Stay in the Kitchen statements directed to her (needless to say, Kouji pressed her Berserk Button constantly).
And in Shin Mazinger, when Boss and his goons insulted Kouji's grandfather one too many times, he promptly beat the ever-loving crap out of Boss, and would have seriously hurt him if Sayaka hadn't interrupted to tell Kouji that his grandfather was in real danger.
And in the Shin Mazinger Zero manga, you do not try and harm Sayaka. Otherwise, Kouji... will not be nice to you.
Beta Test Baddie: Dr. Hell has shades of this. Part of his animosity and resentment towards Dr. Kabuto comes from the fact he thinks Juuzo surpassed him, rendered him obsolete and took all away him when they were younger. All of it contributed to the breakdown turned him into a Mad Scientist. And in the third episode, after his first batch of Mechanical Beasts were crushed by Mazinger-Z, Hell had a Villainous B.S.O.D. since after fifty years, Juuzo Kabuto could still easily surpass whatever Hell did.
Big Damn Heroes: Kouji (and Sayaka, and Boss) pulled this off sometimes. However, the most memorable moment happened in the final episode (and its extended movie version) when a new enemy army appears and proceed to completely overwhelm Kouji. As the Mazinger barely holds itself even a tiny bit together, the Great Mazinger shows up just before the final blow is struck and proceeds to absolutely dominate the new foes. Also something he's fond of doing in remakes, often with a nice big THUNDER BREAK to blast any number of enemies ready to swarm his allies. Also some really nice descending from the clouds shots.
The Big Damn Kiss: In Mazinger-Z vs Great General of Darkness, Kouji is going to sortie with Mazinger-Z to fight a battle he knows he can not win, and thinking he'll die. Sayaka stops him to give him his little brother's birthday gift, and both stare into each other's eyes for a long while... and then Kouji turns around and leaves. However, in the manga version of that moment, though, they do kiss. The pannel itself featured them floating in a void, and flower petals falling around them.
Big Creepy-Crawlies: Several Kikaiju (such like Winder A2 or Megaron P1 and its "brothers") resemble slightly humanoid insects.
"Blackmail" Is Such an Ugly Word: Subverted in an episode. Baron Ashura hijacked a plane and threatened Professor Yumi with killing all passengers if he didn't hand over the plans for the Jet Scrander. Yumi protested that was theft and blackmail. Ashura languidly replied: "Of course it is. What else did you expect from me?"
Blade Below the Shoulder: Mazinger-Z belongs to the second kind (permanently-attached blade). In the last season the mecha got equipped with the "Iron Cutter", two retractable blades stored in each arm. Often he used them in combination with its Rocket Punch to slice enemies from far. On the other hand, several Mechanical Beasts belonged to the third kind (blade replaces hand or arm). For example, Brutus-M3 had a scimitar-like blade replacing one of its arms.
As mazin sounds like majin (demon god) this may explain why Mazinger is translated as Tall Evil God.
Crabstick. Asia directs the beast king armies of Dr. Hill with its Crabstick.
Blood Knight: Some of the Mechanical Beasts -like Spartan K-5, whose A. I. was patterned after gladiators and barbarian warriors- loved fighting with whoever was capable of challenging them.
Blow You Away: Mazinger-Z's Rust Tornado. Also, Stronger T4 and Blowgun P1 were equiped with weapons generated powerful currents of wind.
Body Horror: The Iron Masks (what lies beneath their helmets is not pretty), Viscount Pygman, the Kedora, a lot of Mykene Monsters... Given that this is from the creator ofDevilman, it was to be expected.
Blue and Orange Morality: Minerva-X is a sentient giant robot specifically created to be Mazinger-Z's Battle Couple. Despite— or maybe because— she was created by humans, several of her personality traits (mainly her conception of what love is) are completely bizarre. Because she was created to be Mazinger's partner in battle, she is in love with Mazinger despite knowing it isn't sentient. She also treats the pilot of a Humongous Mecha as if it was another part of the mecha (presumably, the brain). This is expanded on Shin Mazinger Zero, where she (transformed into a Robot Girl) teases Sayaka because she saw Aphrodite (Sayaka's Fem Bot) fighting alongside Mazinger and got jealous, got... all bothered when she was inside Mazinger's cockpit, and she told Kouji she loved him... but she loved even more Kouji piloting the Hover Pilder, and she loved above all Kouji on the Pilder piloting Mazinger. Usually Kouji and Sayaka only shake their heads and accept her like she is.
Sayaka: How... unique...
Blue Is Heroic: One of the favorite colors of the heroes of this universe:
Mazinger Z's arms, legs and head are blue. Diana-A was the second robot of Sayaka, and its whole body was colored with different shades of blue (and its pilot is calmer, more prudent and more kind-hearted than Mazinger's pilot).
And in UFO Robo Grendizer, Duke wore a red-and-blue costume. Koji and Hikaru also wore blue suits. Maria was the only that wore red, but her mecha was mostly blue.
Bookends: Episode 47 starts and ends with the same scene: Ashura and Brocken clashing blades and insulting each other. The only difference is in the first scene Dr. Hell broke up the fight, and in the last scene he is trying to ignore them as he has dinner (groaning about being Surrounded by Idiots).
Mazinger's Photon Beams are one of its most boring weapons, lacking the inherent visual awesomeness and raw power of the Rocket Punch, the Breast Fire or the Rust Hurricane. However it is Mazinger-Z's most used weapon in the series. Why? Because they are powerful enough to have the work done, cost-efficient and can be shot many times in quick sucession (Kouji can't use Mazinger's Finishing Moves recklessly because they overheat his robot and consume a lot of energy). Also, in the original manga Kouji dealt with the enemy by punching it and kicking it and using a weapon to finish it more often than not. Less spectacular? Certainly. Effective, regardless? Definitely.
In one episode Kouji could not use Mazinger-Z since the Pilder was destroyed. So he destroyed one of the Mechanical Monsters of Archduke Gorgon by planting landmines and luring it to step on them. Not so impressive like a giant robot, but effective.
Brain in a Jar: The Kedora. Ken Ishikawa one-shot "The Relic of Evil" revealed that the Mykene controlled his Robeast by grafting the brain of a soldier taught to destroy all no Mykene civilizations into a parasitic organism, and it fused with a robot, giving the Mykene soldier complete control. They would show up later in Shin Mazinger.
Brainwashed and Crazy: The Hero Kouji Kabuto was brainwashed by Viscount Pygman, and later by the Vegans in the UFO Robo GrendizerGo Nagai manga, and the UFO Robot Grendizer tai Great Mazinger movie. Professors Morimori, Sewashi and Nossori also were brainwashed by Baron Ashura into one of the earlier episodes of the original anime series. AND in another episode three workers of the Institute were brainwashed into piloting several Mechanical Beasts. AND then you have the Iron Masks...
Breaking the Fourth Wall: The original manga penned by Go Nagai broke the fourth wall several times. In one of the first episodes Kouji is forced to kill a Mook in self-defense and he suffers a Heroic B.S.O.D. thinking he is a murderer... until another character calms him down stating he was only defending himself and he is the main character and The Hero, so he did no wrong. And in this page Count Brocken complains Kouji is a Combat Pragmatist and yells the main character should not fight dirty and the fans will cry. Kouji was not impressed.
Breath Weapon: Rust Hurricane. Mazinger blows a jet of particle-charged wind from its mouth grill that corrodes the enemy into nothingness. Many Mechanical Beasts also had breath-based attacks, usually expelling out fire, acid or even poison.
In that same episode, Mitsuo, the bullied kid, later decided he would show them what being picked on by somebody bigger than you feels like, when an unknown lady showed up out of the blue and offered him her Humongous Mecha to take revenge (and he agreed. Oh, my God) Of course, that went as well as you would expect.
Calvin Ball: Parodied with Brockenball. It vaguely resembles soccer, but the only established rule is everyone wins. Except the ball. Which is Count Brocken's head. Kouji and his friends played it in the original manga and Shin Mazinger.
Canine Companion: Saijyo (a secondary character who appeared in episode 26) and his female dog, Norako. He was an orphan, homeless boy, and she was her only friend. He was fiercely protective of her.
Character Development: It was not huge but it was there. For example, Kouji's sexism eased up somewhat through the episodes. At the beginning, Kouji flatly refused having Aphrodite modified into a full-fledged battle robot, declaring he does not need aid, and stating to Sayaka's face girls should not fight (Predictably, Sayaka was not amused by this). Several dozens of episodes later, Aphrodite A is utterly destroyed in battle, Sayaka nearly loses it (see Heroic B.S.O.D. example), and a new robot is built for her. Kouji asks the professors endowing it with weapons.
Charles Atlas Superpower: Kouji was a physically average teenager in the original series, but in Shin Mazinger Zero he performs physical feats that should be impossible, possibly due to the constant time travel somehow heightening his capabilities. He does not seem being initially aware of it, though. In the second timeline we see he destroys one robot with one single punch and he panics wondering if he is some kind of monster. In the third timeline he easily dodges the attacks of the Gamia sisters and takes down one of them even though they are several times faster and more agile than a human being (as an amazed Minerva notes).
Chekhov's Volcano: The Photon Atomic Research Institute is located on the base of Mount Fuji. And unlike other shows, this series remembers it is a volcano. Cue battles over or around the crater, the villains plotting set off an eruption in one episode and dunking The Hero and his Humongous Mecha in the volcano in another one.
Chest Blaster: "Breast Fire!". By using the heat sinks on the chest, Mazinger is able to fire an intensely hot blast of heat at the enemy, powerful enough to completely melt an enemy. Other robots have used this move, some in different and more powerful versions including using gravity or freezing methods.
Classical Mythology: Increasingly important in the series. Dr. Hell;s finding several Humongous Mecha in the underground mazes of a Greek island has its basis in the Greek legend of Talos, the giant man of bronze that protected Crete]. Gorgon's Robeasts resembled gods, heroes and creatures found in the Greek myths. And in later retellings of the story (Z-Mazinger and Shin Mazinger), Mazinger-Z turns out to be Zeus and the Emperor of Darkness becomes Hades.
Climactic Volcano Backdrop: Several climatic battles happened next to volcanoes and lava pools. In episode 25 Kouji fought Aeros B2 and B3 next to Mount Fuji's crater, and lava bubbled and spilled out of the pool as they brawled, threatening with engulfing them. In one manga chapter penned by Gosaku Ota, Kouji and Holzon V3 battle took place into the crater of Mount Fuji, with the sheer walls of the volcano as background, toxic fumes rising and swirling around them and magma sizzling and churning under their feet. And then you have the episode where Mazinger-Z got dunked in lava...
Clingy Jealous Girl: Sayaka, sometimes. The most egregious example, though, is "Minerva X", a Sentient Mecha that loves Mazinger Z and is openly jealous of Sayaka's Aphrodite A.
It happened to Sayaka whenever a beautiful girl hang around Kouji: Hitomi, Erika, Misato...
Clothing Damage: It happened to Sayaka in the original manga sometimes (too many times for her liking). Given that it was created by the man who gave us Cutey Honey, it is not surprising. In one chapter, several female robots with blades replacing their arms sliced her dress to ribbons, without actually cutting her flesh or underwear.
Collapsing Lair: In the Final Battle against Dr. Hell, his base crumbled down and blew up. Justified, since a giant robot was actively working to demolish it.
Colonel Badass: Commander Badass, in this case: Great General of Darkness/Ankoku Daishogun, The Dragon of the Emperor of Darkness and commander of the seven armies of the Mykene Empire. He wields a BFS, sports a Badass Cape and a Badass Beard, and he can kick the butt of nearly any Humongous Mecha invented by Go Nagai. He led the army of Mykene Empire, personally or delegating on his generals, and he was A Father to His Men considered unforgivable default intelligence costed the lives of his troops. He fought Great Mazinger because he knew he could win, slicing it with his blade mercilessly as he laughed its attacks off. And he fought Mazinkaiser quite evenly.
Colossus Climb: An interesting example in episode 14 because it is an instance of a villain making this to one of his own monsters. To destroy a Mechanical Beast that Dr. Hell had deemed useless, several Iron Masks climbed up the several-meter-tall giant robot and planted a bomb in its body.
Combat Pragmatist: Kouji, like you wouldn't believe. During his second battle, he is not above of tricking his opponent in believing that he has given up the fight. And he does this several time during the course of the series.
Combining Mecha: Mazinger-Z is the first example -not surprise here- of this trope in Humongous Mecha anime, being of the Mecha Expansion Pack Augment kind: the robot is powered by dropping a small aircraft (the Hover Pilder) onto its head. And then it is combined with a Jet Pack to allow it fly.
Companion Cube: Several times the characters talked to or about Mazinger-Z and Aphrodite A like if they were sentient beings. Sayaka actually had a Heroic B.S.O.D. when Aphrodite A was destroyed. She even hallucinated Aphrodite was calling her. And then you have Minerva-X, an actual sentient Fem Bot and Humongous Mecha could act, think and feel on her own and was programmed to be Mazinger-Z's Battle Couple, and considered Mazinger was meant to be HER Companion Cube.
Context-Sensitive Button: Unbuilt Trope. Mazinger's cockpit was full with buttons and levers, and it is unclear what did what, but every one had a very specific function, and Kouji can not simply press a random button and expect Mazinger Z to do what he wants. The first time Kouji activated Mazinger in the original manga, he nearly demolished half a city because he kept punching random buttons trying to figure out how to handle the damned thing, and nearly got his little brother killed.
Conveniently an Orphan: Kouji and Shiro's parents died on a laboratory accident but in reality only their mother died. Sayaka has also lost her mother.
Convenient Coma: In Mazinger-Z versus Great General of Darkness, Shiro got badly injured and fell into a coma when the ceiling of the room he was in collapsed. He needed an urgent blood transfusion to save his life, and since blood supply was low (what with giant monsters obliterating major cities), Kouji demanded they used his own blood despite his own injuries. Kouji spent the whole night by his brother's side, not knowing if he would live to see another day. Fortunately, Shiro came out of his coma the next day.
Convection Schmonvection: Many battles happened around volcanoes, near volcanoes or in volcanoes, and at least once Kouji was dunked in lava. Since Kouji always remained inside Mazinger-Z, his Humongous Mecha provided protection from extreme heat, toxic fumes and other dangers, but in the episode where Mazinger-Z took an unwilling magma dive it was stated not even Mazinger-Z's armor and heat-insulation could endure that for long, and Kouji eventually would die. The sequels and reimaginations played with the trope as well.
Converse with the Unconscious: Done twice (and subverted in one of them) in episode 52. After Kouji and Sayaka have a serious fight (they fight all the time, but this time was worse than usual), Sayaka refuses to help Kouji to fight, and he gets badly injured. A grief-stricken Sayaka takes care of him in the hospital, talking to him while he is comatose. Later Kouji gets badly injured again and he falls unconscious in the battlefield. Sayaka is cradling his body, crying, begging him not dying and doing an Anguished Declaration of Love... when he opens his eyes and he calmly states he is not getting married to a tomboy.
Played straight in a chapter of the Gosaku Ota manga. Sayaka is unconscious and Boss stays by her and talks to her, before finally leaving for battle, stating that dying like a hero is all he can do for her.
Also played straight in the Mazinger-Z versus Great General of Darkness movie. Shiro gets caught under a collapsing ceiling and falls into a coma. He needs a blood transfusion and Kouji insists on them using his blood. As the medics are performing the transfusion, Kouji talks to his little brother, reassuring him everything will work fine.
Cool Airship: Guru, Count Brocken's aerial fortress. It appears for first time at the episode 40.
Cool Bike: Kouji is a Go Nagai main character. Go Nagai main characters ride bikes. Sayaka and Boss also ride bikes.
Energer Z, the "prototype" design of Mazinger, was controlled by a motorcycle driven into the head; for the final version Nagai replaced it with the Hover Pilder because he was concerned the bike would look like a rip-off of Kamen Rider.
Cool Helmet: Kouji and Sayaka wear one. Kouji began wearing it (along his Latex Space Suit) after his first battles since his head got hit several times.
Cool Old Guy: Dr. Juzo Kabuto. He escaped alive from Hell's assassination attempt (two in the Gosaku Ota manga). He built the eighteen-meter-tall, One-Man ArmyHumongous Mecha that was the last hope of humanity. He saved his son's life, turning him into a cyborg. When Ashura blew up his mansion, he got half-buried under several metal rafters, but managed to survive until his grandsons showed up and he could hand Mazinger over to Kouji. And in the manga and Shin Mazinger he overlaps this with Crazy Awesome.
Cool Ship: Salude and Bood, Baron Ashura's submarine fortresses.
Covers Always Lie: An episode's title is: "Kouji Dies In Lava!". It did not happen in the story.
Crazy Enough to Work: Kouji's plans can be careful and thoughtful strategies, but many times his plans are an Indy Ploy or... this. One example happened in episode 32: Mazinger Z got the crap beaten out of it by Gelbros J3, a flying, three-headed dragon-looking Mechanical Beast. Mazinger could not fly yet, so Kouji could not fight back. His plan was... equipping Aphrodite A with even bigger Torpedo Tits. During the battle, Mazinger latched on the giant missiles and was propelled skywards, where Kouji could reach the Robeast and shoot it down.
Crazy-Prepared: In one episode, an enemy was unceasingly shooting missiles at the Hover Pilder to preventing Kouji from docking with Mazinger. Kouji pressed a button, and his vehicle let go a trail of smoke to make the enemy believe he had been shot down and stop shooting.
Crippling Overspecialization: Several Mechanical Beasts had a fighting style entirely based on the weapon or device they were equipped with, and when they lost it, the battle was finished shortly after (even though they usually tried to put up a good fight). There are several good examples: Jinray S1 (episode 24) best weapon was its amazing flight speed (Match 5!) that it used to dive at its enemy, striking it with lightning bolts and missiles and fleeing away. Since it could hit him and and run away before he could even spot it, Kouji got a very hard time... until he blew up one of its rockets. Unable to perform its hit-and-run tactics, Jinray was helpless; Holzon V3 (Episode 17) was armed with huge drills to burrow underground and set off earthquakes, making it deadly... unless you forced it to return to surface, where it was a crappy fighter; Kajimofu T7 (episode 48) combined both its palm blasts and its missile launcher to hit its adversary. It was a very efective, destructive tactic... but when Sayaka and Boss ripped its arms off, the battle was over because its missile launcher was not strong enough on its own.
Crucified Hero Shot: Both Kouji and Mazinger are subjected to this several times in the course of the series. So did Shiro, Boss, Nuke and Much. Ashura seemed to love this Trope. Also, Devilman himself in the movie Mazinger vs Devilman.
Crush Blush: In the original manga Kouji and Sayaka blushed several times when they talked to each other.
Cry for the Devil: Neither the original manga penned by Go Nagai nor the anime series went into the past and motivations of the villains. The manga penned by Gosaku Ota and published simultaneously with the tv show finally revealed what they were. In one of the last chapters, as Dr. Hell is making preparations for the Final Battle, Dr. Hell begins to narrate what his early life was like. We learn during the flashback that he was born in a very poor family. His mother never wanted to have a child, constantly stated his existence was a bother for her and beat him constantly as his father did nothing. No child wanted to play with him because he looked ugly and weird. Looking for a way out of it he turned to books. He became very intelligent, began to get excellent grades in school... and then his teachers accused him of cheating and several of his classmates bullied him. He grew up without friends until he got to college, when he befriended someone who appreciated his intelligence and he fell in love with an exchange student. Shortly after he found out they were a couple and his frayed mind was already so paranoid he thought they were plotting against him to backstab him. After another unpleasant incident where he got beaten for a good deed (a little girl slipped in front of him and he caught her, avoiding she hit the ground and got hurt. It was a well-meaning, innocent act. However her parents thought he was molesting her, and her father pummeled him) his mind finally snapped and he decided Humans Are Bastards and one day he would wipe the world of idiots and everyone would have to kneel before him.
Cut-and-Paste Translation: Mazinger-Z infamously got this sort of treatment after GoLion/Voltron proved successful, and got it from people who didn't care a whit about maintaining the show's integrity. Needless to say, there's a reason few people love Tranzor Z these days, and Go Nagai was frustrated enough with the failure that it took over a decade for any other Dynamic Productions show to reach America.
Cut Lex Luthor a Check: Dr. Hell is wealthy enough to build dozens of giant, humanoids war machines, Doomsday weapons, squad of cyborgs, several HQ, aircrafts, submarines... It was kind of justified in the Ota manga when Dr. Hell revealed shortly after finding the old Mykene's mechanical warriors, Count Brocken took over several ancient European Mafia in order to earn cash for Hell.
Cyborg: All villains (except Dr. Hell) were cyborgs: Baron Ashura, Count Brocken, their Mooks... All of them (except Archduke Gorgon's) were created by Hell himself. Usually he fabricated his cyborgs by modifying corpses, replacing damaged parts with artificial limbs or organs and implanting cybernetic components in their brains to create obedient, brainwashed slaves (and there was at least one scene in one of the manga versions where Baron Ashura killed many people off, gloating they would be transformed into cyborgs and turned into his/her slaves. Now you know what happened to all people died when a Mechanical Beast attacked). However, in at least one instance he saved the life of the subject (Count Brocken) by turning him into a cyborg. Other cyborg characters were Kenzo Kabuto and in the Gosaku Ota manga Kouji Kabuto himself was turned into one by the end of the series.