From the original series: Krillin's first death, and Goku getting to him too late. Heartbreaking.
Worse, in the anime: Goku, who's a Big Eater, doesn't even touch his food, struggling to shake off the fact that a simple friendly task of Krillin offering to get his 4-star ball back to him could lead to danger. He then flips out, after hearing Krillin scream and runs back to the contestant room, and the first thing he sees is Krillin's body on the ground. The announcer, who was also attacked, explains a monster came and fought Krillin and stole a list. The gang run back to see what happened. Goku tries to look for a heartbeat, but hears none. He then announces that Krillin is dead, and appears to fighting back tears, while deeply enraged. It's actually one of the first times we've seen Goku cry, and not in joy like the arc before.
Even the blonde Lunch, who introduced herself to Goku and Krillin by shooting at them, was sad and sorrowfully carried his body in her hands.
"Death 1.5", where he's gored by Freeza's first transformation, but is barely saved by Dende. Especially with how long it took him to expire.
His second death. Quick and senseless, but still just as wrenching.
When Goku transforms into a Super Saiyan as a result of Krillin's death.
Although, it was a Heroic Sacrifice as he acted as a decoy to protect his family which definitely has some emotional merit. It gets really sad when you realize this ends up being a Senseless Sacrifice since his wife 18 and his daughter Marron were the VERY NEXT victims of Super Buu shortly afterwards.
His fourth death, in GT when 17 is trying to get 18 to come back to him. Krillin (An aged man at this point, daughter Marron beside him) is telling him he has no control over her anymore, she's not a part of him, and she can make her own descisions. 17 doesn't like this. So he blows a hole through Krillin's chest, blowing him back and killing him. What sets it off is Marron and 18's reactions. Marron's shaking his limp body crying "Wake up Daddy... wake up!" while 18 is begging for him not to leave him, crying while a montage of scenes between the two are shown. She sheds a few tears and whispers a soft "I love you" before rushing at 17.
What's even worse is if you think about the whole thing from 18's perspective. She likely hasn't seen her brother in about two decades, he shows back up, tries to convince her to go right back to the obviously-painful situation that they were in all that time ago, but at this point she has friends and new family. Then the brother she loves kills the husband who she legitimately loves, despite her Sugar and Ice Personality flaw that sometimes makes it seem like she doesn't. And then he tries to kill her daughter. She's not a very emotional person, but that just hurts.
King Vegeta's death: the guy is trying to rescue his son from the clutches of an monster like Frieza and dies trying.
What makes it worse is that Vegeta doesn't even know how awesomely brave his dad was when he died. He probably thinks his father was on the planet when it happened.
Ever since he was four, Gohan's childhood has been nothing but struggle. Unlike his father, Gohan never wanted to be a fighter, he was just constantly pressured with the responsibility to do what no one else could.
A little too subtle to notice, but the fact that Chi-Chi blames herself for being so stubborn in Gohan's raising and her stance against his martial arts training, and that as a result she indirectly caused Goku's death at the hands of Cell isn't too easy to face. This is the very reason she is seen training Goten.
Every time this song plays in Dragon Ball Z, it's almost guaranteed to make you cry, as it accompanies some of the most dramatic deaths in the anime, including Piccolo and Vegeta's.
The end of Mystical Adventure. When Upa gets the courage (from Goku) to ask Shenron to revive his father. It's more of a so happy it's sad moment. really. What really makes this scene is the song Dragon Ball Densetsu playing over it.
When the Masked Fighter is revealed to be Gohan Sr. in Dragon Ball. Goku begins to cry as he hugs his grandfather. Bulma even says "Gosh, even Son's crying!" A rare occasion indeed.
A particularly heart-wrenching line from this scene, in the dub: "I looked for you everywhere and I couldn't find you!"Oh, Goku.
This is even sadder when Goku thinks he'll be reunited with his grandfather again, but realizes that Grandpa Gohan can't stay and has to return to the afterlife.
"Pathetic... to think that the Demon King Piccolo should fall protecting a child... I have been... contaminated by the decency... of both you and your father... Gohan... though I have been... cruel towards you... you remain the... only person who has ever spoken to me... with kindness... These last few months with you were not that bad... Please don't die... Gohan..."
It's even sadder in English (Ocean dub, kept by Funimation until Kai) version, especially one of Piccolo's last lines: "Gohan, you're like the son I never had."
The moment leading to Tenshinhan's Heroic Sacrifice in the Saiyan Saga certainly fits in. As the battle gets intense against Nappa, an injured Tenshinhan sees his friend Chiaotzu, who has already died, saying sorry for not being strong enough, and then fades away. Then he regains the strength to stand on his feet:
Tien: Chiaotzu, I won't let your sacrifice be in vain, I promise! This Saiyan goes down right now... or I'll be...with you again soon!
A montage is then shown of the times they had together, and it ends with Tenshinhan firing his last one-armed Kikoho at Nappa, which only damaged parts of his armor, and a few scars, before the triclops passes away.
The Abridged Series still manages to keep this Tear Jerker intact.
Nappa:(to Piccolo and Krillin) At least you didn't uselessly self destruct like that Pokemon. Tenshinhan:' You stupid... ugly... Son of a bitch. His name was Chiaotzu! KIKOHO!"
This can of course induce Mood Whiplash if you're a Pokémon fan. Having seen Selfdestruct fail for various reasons will do that.
Krillin: (Teary-eved) Poor Tien, he used up his life and that attack didn't even faze him! Goku!! Please hurry!!
And before that... Yamcha's death. Especially since Krillin actually goes over and confirms he's dead. You see Puar crying against the TV, calling out to him... and then the POV switches to a shivering, pale, almost BSOD-ing Bulma. Her scream of despair as she breaks down in Roshi's arms is tear jerking.
Watching warrior after brave warrior that we have come to love during Dragon Ball being slaughtered by Nappa during the Saiyan Saga. Particularly heartwrenching is the Senseless Sacrifice of Chiaotzu, whose Super Power Meltdown did not even scratch the Saiyan brute, much less hurt him. It was a wise narrative choice on Toriyama's part for Vegeta to not have personally killed any of the heroes, allowing the possibility of redemption in the audience's eyes for the Warrior Prince.
This is even more moving in Dragon Ball Kai considering that Chiaotzu knew that he couldn't defeat Nappa and that he had been revived with the Dragon Balls once, and wouldn't be able to be revived again, but the real moving moment is what Chiaotzu says right before he dies:
Chiaotzu: Tien, just... just don't let him kill you.
The real heartbreaker is watching Chiaotzu knowingly sacrifice himself in an attempt to prevent Tien from dying, but shortly afterwards, seeing Tien using the last of his energy to try to avenge Chiaotzu's death, and dying in the process.
After the Saiyan saga, watching everyone mourning the loss of the fallen Z-fighters and moving the coffins with their bodies onto the ship. This scene is made even more powerful with the beautiful song playing in the background of Dragon Ball Kai.
Gohan's training in the wilderness during the Saiyan Saga really makes you want to grab hold of the kid and hug him. He's out there all alone with only Piccolo keeping an eye on him to monitor his training from afar. In one episode while hiding in a cave he discovers he's not alone as a Dinosaur is with him, luckily its a vegetarian and is wounded. Gohan helps it heal up getting it food and puts a salve on its wound like Goku taught him. So you think Gohan's made a friend right? Wrong, another Dinosaur this one a T-Rex shows up and attacks the other one. Gohan tries to save him but gets knocked out by the T-Rex. When he comes to, he sees the bones of the other Dinosaur as the T-Rex had eaten him. Seeing the tears form in his face over what happened really gets you.
One of the most heartbreaking fillers would have to be the one when Gohan washes up on a beach and is found by the local orphans. The episode is adorable in that Gohan makes friends with many children his own age for probably the first time in his life. But just as Gohan gets comfortable with his new friends, some people from the local foster home come to take the kids away. Gohan then meets the leader of the kids, Pigero and helps him protect the orphans. One of the adults tries to tell them that if they come with them, they will go to a place where they will get new clothes and hot meals, but Pigero believes that she is lying and tells her off. Later that night, Gohan explains he still has a mother, and was on his way to see her before he met them. Much to his surprise, the other children tell him it doesn't really matter to them whether he's an orphan or not. When Gohan tells them where his house is, they all come up with a plan. The next day when the adults leave the van, they are immediately bombarded with rocks. With the men distracted, Pigero commandeers it, then signals to Gohan and the others. They all pile in just as the police show up. Pigero orders the kids to scramble and they all rush to get away, but they are surrounded. While kids are grabbed they fight to keep them from being taken. Unfortunately, it's not enough as the police soon overwhelm all of the kids except for Gohan, who barely manages to free Pigero. Then poor Pigero, considering the future of the other orphans, grabs Gohan and they escape in a stolen police-car and drive away with tears in his eyes, to the betrayal of the other kids. After they've escaped Gohan demands to know why Pigero left the others behind, Pigero tells him his reason is because he cannot provide enough for them and that maybe the people from ''the home'' can do more for them. After he drops Gohan off, Pigero drives away as he sets off to start a new life. It may have only been a single filler episode but GHEEZ, RIP MY HEART OUT WITH YOUR HEARTBROKEN PUPPY-DOG EYE'S WHY DON'T YOU!
And later on, he finds out he's near home and rushes up the road a smile on his face and sees his house and his Mother inside. He wants to go in and hug Chi Chi who he hasn't seen in half a year but slowly he realizes what he has to do, his smile fading he turns and runs away from home just missing his mother who sensed him for a moment. After a distance he discovers Piccolo looking down on him and tells him that there will be nothing left if the Saiyans are not stopped and Gohan knows this, abandoning his chance at a normal life so he can protect her.
It's a scene that's only found in the anime, but during the Saiyan battle, Piccolo berates Gohan for panicking behind a rock when a good opportunity to attack Nappa while he was defenceless presented itself. While Krillin defends him by saying he's only five years old at that point, and the fact he's even on the battlefield is remarkable enough. Piccolo at that point denounces Gohan as a coward, declares he's wasted all that time training him, refuses Gohan's request to train him in a three-hour break, and finally dismisses him. Krillin tries to call Gohan back as he walks off, and Piccolo wont even face him. However, Piccolo sadly contemplates that he already taught Gohan everything he knows, and maybe as cruel and harsh he was being, that was his way of deciding that Gohan was probably better off going home. Granted the scene was ruined by Mood Whiplash and Nappa's comically dickish behaviour, but apparently in the Hyperbolic Time Chamber, it's shown that Gohan's guilt for coming up short back then still affected him.
Dragonball Z - Namek Saga
In Embodiment of Fire, when Freeza drowns Goku, while he was slowly dying he has a nightmare of Freeza killing everyone he loves. It was heartbreaking in the Dragon Ball Kai version to hear him so distressed when he cries out Gohan's name only to get no response.
Vegeta breaking down and crying Manly Tears as he lays dying, his heart punctured by Freeza, telling Goku the story of how their race was murdered by the tyrant.
"Defeat Freeza... I beg of you... Freeza must die... by... A Saiyan's... Hands..."
"Kakarot... Listen. Destroy... Frieza. He made me what I am... don't let him do it to anyone else... whatever it takes... stop him... please..."
The fact Vegeta is reaching out to Goku with blurred vision from tears makes this all the more poignant. This is directly after he's told Goku that Freeza took him when he was just a child and used the threat of killing his father to keep Vegeta under his thumb and then did so anyway.
Same scene yet again, but this time, the FUNimation dub of the uncut version of Kai takes this up a notch, while staying close to the translation of the Japanese text from the aforementioned original Z:
[about Frieza] "I beg you, Kakarot... Please beat him... for me. For the pride of our race... Please. He must die by... a Saiyan's... hands..."
In all examples, the true Tear Jerker moments of the scene are that Vegeta even when dying does not ask for Goku's pity, but simply to be avenged as he reveals the evil the Saiyans did under the manipulation of Freeza making the viewers realize that they were loyal to him, but Freeza killed them to protect his own megalomaniacal agenda.
What hits home in this poignant scene is that though Vegeta is telling the story as he is dying of a punctured heart, Goku tries calming him down, warning him not to waste his breath in talking lest he end up killing himself; but Goku (and the audience in particular) knows that his warning could be useless, and that Vegeta is about to die anyway. The sad music in Dragon Ball Kai (along with slightly improved dubbing) makes this scene all the more heartbreaking.
This scene is made even more powerful considering what Goku said right after Vegeta's death:
Goku: Goodbye, Vegeta. You weren't as cold-hearted as you thought you were. A heart of stone couldn't have shed tears like that. You must have been holding them back your entire life. (sadly) I'm the only one left. (creates a grave) Now I see. You weren't grieving for your own death, or the death of our home planet, you were grieving because he (Frieza) made you what he wanted you to be! You never had a chance to decide for yourself! (lays Vegeta to rest) Well I still respect you. You may have made a lot of mistakes, but now I see that they weren't all your fault. You had the fiery will of a Saiyan. Please share that with me now, because I need it. Thank you for saving my son's life and buying time for me to recuperate. I will do all that I can to carry out your wish. (to Frieza) Vegeta's right, you have no honor! For him, and for everyone else you've destroyed, I am going to finish you!
The original version is even more moving, as it is a pivotal point in Goku coming to respect and take pride in his Saiyajin heritage.
Goku: To think that a man as yourself would shed tears... and to beg... what you endured must be unimaginably frustrating. I understand... moreso than having your entire race murdered; it is to have your free will and pride ground under his feet; a pain I cannot start to imagine. I hated you so much, but I've always respected you for proudly defending your race's honor... Now lend me some of that pride, for I am a Saiyajin who grew up on Earth!! (Turns to Freeza) For the Saiyajin race you exterminated, and for all the Namek-Jin you murdered, I shall defeat you!!
The music that plays (or played?) in the background of this scene (and the other scene below) in Kai? "Tears of Grief", accompanied by a Lonely Piano Piece. Give it a listen... and please try hard not to sob like Vegeta... or at least bring your Kleenex along.
Not long after Vegeta's death, and Goku is on the brink of death at the hands of Frieza, Vegeta's spirit appears (either in naked form in the original version and in Kai (with the bottom half obscured in the latter), or shirtless in the FUNimation dub), telling him to remember what Frieza had done to the Saiyan race and their home planet and encouraging him to destroy Frieza. Also accompanying Vegeta are his father, followed by Goku's father Bardock.
The FUNi dub of the uncut version of Kai is the icing on the cake:
Vegeta:[voice only] Kakarot! How dare you give up! You're a Saiyan warrior, take some pride in your heritage! Goku:[lamenting] I... I am not a Saiyan like you! Vegeta:[voice only] Please. Stop trying to convince yourself; you personify our race! Goku: Just stop! None of that matters now anyway! Even together, we— [scene cuts to Vegeta's body lying on the ground; Goku gets shocked and confused] Uh... Vegeta... [scene then cuts to Vegeta's grave before cutting back] Where—? Vegeta:[appears in spirit form] The blood in your veins, that perfect instinct for battle, there's no denying what you are. Reach down deep, feel the pain of those of us who failed! Your brethren were all decimated, your home world lost! Does it not enrage you to stand up to the man responsible for driving us to extinction?! My father.... your father. Both dead... [he then transforms into his younger self before continuing] Kid Vegeta: Both dead. Killed by him... Lord Frieza. You are the last of our kind, Kakarot. Everything we were survives now, only in you. [brief scenes of Bardock and then King Vegeta getting killed, then back to the adult Vegeta] Vegeta: And he won't rest until every trace of that has vanished, because he's haunted every day and night by a single overriding fear: [transforms into Giant Ape Vegeta] Giant Ape Vegeta: That the legendary Super Saiyan will rise up from the ashes and obliterate him! [reverts to normal Vegeta] Vegeta: I dreamt... [his father, King Vegeta, accompanies him] Vegeta & King Vegeta:[in unison] I yearned to be the one to avenge us... [Bardock now accompanies them] Vegeta, King Vegeta, & Bardock:[in unison] Yet he battled and broke me just as he did the others. You cannot know the torment I've died! Vegeta:[now alone] Unless you're the one to finish this, we'll be lost... lost forever... to the memory of time. [vanishes]
The Namekian grand elder's (a/k/a Guru) second death. Despite the happy ending (living just long enough to appoint a new elder, most of the Namekians coming safely out of the struggle on their home planet, etc.) the reactions of his family (and the few Earthlings involved) surrounding him just adds that extra touch of emotion.
The first death of Guru was particularly moving, especially with the Bruce Falcouner music playing as you saw Dende crying and Guru's lifeless body sitting in the chair.
Dende's death by Frieza on Namek. It was sad enough watching his brother Cargo killed by Dodoria earlier, but this took it to a whole new level.
In the manga, it was Freeza the one behind Cargo's death. In the exact same way, finger beam too fast for anybody to react and help the kid.
The scene where Goku first transforms into a Super Saiyan in Dragon Ball Kai: It's not enough that Krillin gets launched up into the air and then blown up - worse if you notice the blink-and-you-miss-it frame of Krillin's chest heaving as the energy ball expands to blow him up from the inside. Poor Gohan, who just lost an Honorary Uncle, is standing over the unconscious body of his mentor looking like a deer in headlights while Frieza threatens his life next. Goku is off to the side with his back turned, shaking with rage, and the only words he can get out of his mouth are "You ruthless... heartless...bastard...I WILL MAKE YOU SUFFER!" As if the impact of hearing those words coming from Goku of all people didn't do it, as soon as he transforms, he turns to address not Frieza, but Gohan, telling him to leave. Previously, it had seemed to mean, "get out of here, kid, the fight's about to get really ugly." But the Dragon Ball Kai version drops this line:
Goku: Do as I tell you! Right now - before I LOSE WHAT LITTLE SENSE OF REASON I HAVE LEFT!!
And it's that moment that you realize that Goku has no idea what is happening to him and doesn't trust himself around his own son.
This speech that Goku made for why he is letting Frieza get to 100% power in Kai:
Goku: Krillin can't be brought back to life a second time and I refuse to take the death of my best friend sitting down! He was a good man with a good heart! The fate this bastard dealt him was the last thing he deserved! Before I am done with him, he will bleed.
Dragonball Z - Garlic Jr. Saga
Filler it may be, but in the episode 'Krillin's Proposal', the final minutes are wrenching: watching Krillin realizing that Maron would have agreed to marry him and then running off with another guy moments later is bad enough, but the final scene where he tries to laugh it off with his friends but the audience (and perhaps Gohan as well) can see the tears hidden behind the sunglasses is just heartbreaking.
Dragonball Z - Android/Cell Saga
Android 16's dying speech to Gohan:
"Gohan... let it go. It is not a sin to fight for the right cause. There are those who words alone will not reach, Cell is such a being. You are gentle, you do not like to hurt. I know because I too have learned these feelings, but it is because you cherish life that you must protect it. Please, drop your restraints, protect the life I loved, you have the power, my scanners sensed it, just... let it go."
The original Japanese speech is just as heartbreaking and poignant:
"Son Gohan... it is not a sin to wage violence for a righteous cause... some people simply cannot be reasoned with. Let your feelings flow free, and unleash your power. I understand your pain, but there is no need to hold back any longer... The forests and animals that I love so dearly... Please protect them for me... I'm counting on you."
Gohan going SSJ2 as "Day of Destiny" plays in the original version.
Similarly, everyone's reactions when Cell blows up Android 16's horror would lead one to think he'd been unofficially absorbed into the crew. Even Bulma, who just got through explaining how she and her father removed his bomb due to distrust of the Android, screams in horror when she sees what Cell does to him.
In a series where Death Is Cheap the fact that Android 16 WAS NEVER REVIVED hits very hard.
Goku's second death. His Heroic Sacrifice might not get you, but Gohan's anguish afterwards certainly will ("It's all MY FAULT!!!!"). The episode is aptly named Gohan's Pain.
The punch to the gut comes in if you catch the fact that Gohan, by this point in the series, had started to call Goku "Dad" or the more formal and mature "Father." He's still in SSJ2 mode, he just literally kicked the shit out of Cell and caused him to have a Villainous Breakdown. But, just for that one moment, he snaps back and becomes the scared little kid from the first few episodes of the series.
Goku's last words on Earth: considering how infamous Goku is for being gone a lot of the time, and the whole Arranged Marriage thing, there are always people skeptical about how much Goku cares about his wife, and sometimes even his son. But after saying goodbye to his friends, and getting ready to teleport...
Krillin's reaction to Goku's Heroic Sacrifice is quite heartbreaking as well. The first time Goku uses Instant Transmission to teleport to Semi-Perfect Cell he let's out a Big "NO!". (In the Japanese version he screams Goku's name.) And when Goku teleports himself and Cell away he falls to knees and tearfully calls Goku's name again. It really does put into context how much Goku's friendship with Krillin means to him.
Goku: Goodbye, friends.
Krillin: Goku, wait, don't leave us...
Although the fact that the next thing we see him do is nervously trying to explain himself to King Kai killed whatever drama that moment had.
In one scene during the Cell saga, Cell returns and Gohan is fighting him. As his Kamehameha wave is being overpowered by Cell's, we see Goku speaking to Gohan and telling him how much he believes in him.
Similarly, one can't help but feel for Krillin, Tien, Yamcha, and (especially) Piccolo, who all attempt to help Gohan by blasting Cell, only for the latter to incapacitate by simply powering up more so that his energy overwhelms them. They succeed in distracting him momentarily, but after they get blown away for the last time, each of them can only apologize for not having the strength to help more. Thankfully, Vegeta blasts Cell at the last moment, giving Gohan the opportunity to strike the killing blow.
The English dub of the end of the Cell saga, with Vegeta admitting to himself that he could never be as great as Goku because of his recent Heroic Sacrifice and resolving to stop fighting was hard enough, but the final scene in the episode "Save The World" is especially saddening due to the narration, and Goku's image laughing in pride from the afterlife.
What really drives this one home is Trunks' reaction. On the one hand, he's much too cool to let his best friend see his papa hug him, but it's a very happy kind of embarrassed.
Not to mention Goten's reaction of looking innocent and sucking his thumb.
And his last words especially.
Vegeta: Trunks... Bulma... I do this for you. And yes, even for you, Kakarot.
This is exactly why so many people were so upset that this ended up being a Senseless Sacrifice.
The others' reaction to learning of his and Gohan's deaths. Especially Bulma and Videl.
It's specially hard with Bulma, as she is surprisingly not very prone to crying. It was only that bad when Yamcha died in the fight against the Saiyans.
Also, when Goten and Trunks were crying over the loss of Gohan and Vegeta. Goku then tells then to get a hold of themselves and that they were Earth's only hope. It may have been harsh, but Goku was trying to get them to pull themselves together because there was no time for crying.
Goku leaving during the Buu saga. He's managed to pass on the fusion technique and now his time on earth is up and he has to go back to Other World. So we see Goten speechless, and giving him one last hug, and trying so hard not to cry, and it's all set to ridiculously relaxing music. GOD JUST RIP MY HEART OUT WHY DON'T YOU.
This is specially harder when you read it on the manga, as Goten wasn't as readily welcoming to his father's return in the first place.
On top of that, the scene where a meek Goten runs up to embrace Goku before the World Tournament was only in the anime, in effect elevating this moment to Final First Hug status for the two if you're going solely by the manga. Either way, seeing Goten curl up into a ball in his father's arms as he's forced to part with a father he never knew until that very day (keep in mind that Babidi's plan to revive Majin Buu massively derailed Goku's one day to return to the world of the living) will do a number on your tear ducts.
What happens to Bee, Buu's dog. That was before Buu managed to heal the dog, of course.
The worst part of the whole ordeal was seeing Majin Buu's devastated expression of shock and trauma as he saw his dog Bee get shot. It's the first time his eyes were open when he WASN'T responsible for a violence act, which made this scene both a literal and figurative eye-opener for the reformed Majin Buu.
When Buu is screaming at Mr. Satan to take the dog and leave, he knows what's happening, he knows he can't stop it, and he's desperately trying to keep his friends from getting hurt, It's just heartbreaking.
Majin Buu: Go away. Take Bee and go. Run.
(Mr. Satan seems shocked, then bemused)
Mr. Satan: What do ya mean, Buu? I'm your friend!
(Walks up to Buu, to reach out his hand, but Buu swats it away)
(Steam explodes out of Buu's head) Majin Buu: GO NOOOOOOW!
(Mr. Satan scared out of his wits) Mr. Satan: R-r-right! Okay!
(Mr. Satan runs out of Buu's house with Bee in his arms)
It wins, leading to a mass murdering, gluttonous brute, who, after absorbing Piccolo, gives Gohan a really nasty Breaking Speech; and later reverts to its omnicidal maniac self, one wonders if the Good Buu is being forced to experience this with no way of preventing this.
The end of the episode "End Of Earth" where Kid Buu uses his Planet Burst attack to destroy the world and Goku and Vegeta who are holding Hercule, Dende, Bee and Majin Buu, look behind them and see Buu's attack swallow Piccolo, Gohan, Goten, and Trunks while they are powerless to save them from being destroyed along with the Earth before they escape to the Kai's planet.
Mr. Satan tearing up when he finds Fat Buu after Kid Buu spits him out. "Please Wake Up... you're the only friend I have!"
And that line really puts Mr. Satan's entire character into perspective. Although his Fake Ultimate Hero status has made him essentially the most famous man on Earth, other than Buu, he has no friends.
Indeed. His wife is dead, his daughter knows he's a liar, and he knows that all those fans love the lie he created, not him. Were the truth ever to come out, they would all abandon him.
Bruce Faulconer helps to create a particularly heartbreaking one with one of Hercule's conversations with Super Buu. In it, Super Buu has completely forgotten who Hercule was and has been consumed by the evil that's taken hold on him. Hercule is desperately trying to get Super Buu to remember who he once was by reminding him of his promise to not kill anymore, as well as how much he loved Bee, only for Super Buu to maniacally laugh in his face. Sad in both versions, but it was Bruce's music that really drives home how completely and utterly destroyed Buu's kindly side has become, as well as the sense of loss and desolation throughout the whole conversation. See here.
In the Majin Buu Saga, after Vegeta knocks Trunks unconscious so he can fight Buu alone Goten, understandably confused, freaks out and demands why he did it. This might just be mostly due to the voice acting, but as soon as he gets to "Why did you hit him? Why did you hurt him?" ALWAYS gets to me. Just how innocent he is and how confused he is really comes out there.
Of course his line just before Vegeta knocks him unconscious is heartwrenching as well, "You're his dad! Dad's aren't supposed to do bad things to their sons!"
This may seem minor, but there's a scene in the Buu arc when Gohan scolds Goten for allowing himself to get hurt and he says "Do you know how mad mom would have been if I went home for dinner and told her you were dead?". It also doubles as Fridge Horror because Gohan may have still been traumatized with his experience after fighting Perfect Cell, which may explain why he was so angry and worried for his little brother.
Let's not forget about Buu turning Chi Chi, of all people, into an egg and killing her by stepping on her while her son, Goten, watches in horror. Whether you like Chi Chi or not, it's very traumatizing and horrifying for someone so young as him. May also count as Alas, Poor Scrappy for those that despised Chi Chi.
When Goku is fighting Kid Buu in the last few episodes. Throughout all of Dragon Ball Goku never ever stopped fighting, never gave up, and wouldn't stop. This was the one time it was too much. Goku could NOT win. Pretty much the strongest anime character of all time is getting his ass handed to him by a LITTLE PINK BUBBLEGUM KID. Goku stomped a planet destroying tyrant into the floor. Avenged his entire race, done pretty much everything, and he finally is bested by Buu... I cried harder than ever.
How about Piccolo's reaction when Gohan was (apparently) killed by Buu? When he first overheard Babidi gloating about it he actually let out an audible gasp - which, given the character, says a lot. Then, a little later, when Goten (who didn't know) said, "If I were Gohan, you'd let me go," the look on Piccolo's face is just... heart-wrenching. The beatdown he gave Babidi later, accompanied by an enraged lecture, only serves to hammer the point home.
Vegeta's reaction to Gohan's apparent death also counts. The way he says to Fat Buu "So you're the one who killed Gohan" borders on Tranquil Fury, but the snarl of Papa Wolf rage is still there. And for a man like Vegeta that says a lot.
The speech Goku gives when trying to get Vegeta to fuse with him:
Goku: Wake up! Majin Buu's eaten everyone we care about! Everyone is gone! Even Bulma! They've become part of Buu! They can't even die! I just thought the least we could do is put our old differences aside, just this once, and really work together! We owe that to our teammates! Our families, Vegeta! Our friends! Look, you've always talked about our Saiyan race, how we're the last of a mighty people. Well, it's time we accept we're starting a new race, one that can be just as strong, just as proud! But not if we're caught up in so much of our old birthrights to see what we have right in front of us! We've lost our old race, Vegeta! Let's not lose this one too!
On the last episode of Dragon Ball Z when Goku decides to train Uub, Pan cries to Goku and begs him not to leave.
How about the entire final scene of "Bardock: Father of Goku"?
Oh God, YES. Or even earlier, when Bardock assists the dying Tohma in his last moments and then starts using the cloth he used to clean up Tohma's blood from his face as a Tragic Keepsake headband.
When Bardock and grown up Goku meet and talk to each other. It's very brief but still tearjerking. Especially the part when Bardock reached out to Goku.
Goku telling his father it's not too late to have a change of heart and make a difference. While he didn't save himself or his home planet, Bardock managed to repent.
This is even more moving because of Bardock's last words:
Bardock: "My... son... lives... on."
The movie: "The History of Trunks." Enough said.
Gohan's death in the Trunks special.
Gohan final stand before his death is one big tearjerker. He knows he will most likely die, but goes out to fight the androids one last time anyway. It is especially tragic since Gohan can go toe-to-toe with one of the androids, but not both, which is probably why the androids chose to kill him this time. It is even more tragic when you consider that Gohan has the power to destroy the androids if his father had lived long enough to train him like his counterpart in the main timeline. Not only did Gohan die without killing even one of the androids, but his endless potential was also lost forever.
This is what triggered his Super Saiyan transformation; what makes it worse is that despite this, he's still no match for them and they allow him to live to satisfy their own sadistic pleasures. Trunks had just gotten stronger, but it was completely pointless.
Much like his mentor before him who turned Super Saiyan after witnessing his own friends' deaths, but was still powerless to avenge them for years before dying a dog's death.
The reactions of everyone at the beginning as they try to come to grips with the fact that Goku is truly and irrevocably dead. Yes, even Vegeta.
Also Gohan's death and Trunks's first SSJ transformation.
Eric Vale's brilliant performance makes that scene incredibly powerful, which makes the moment truly unforgettable.
In Cooler's Revenge, seeing Goku, him and his friends utterly defeated, cupping in his hands a bird which died in the battle between Goku and Cooler, sobbing about how it didn't even do anything wrong.
Surprisingly enough, one of the most powerful ones in the franchise happens during Dragon Ball GT.Because the Black Star Dragon Balls have not been returned to Earth, the planet is set to explode. Though the team has managed to evacuate everyone to the nearby Tuffle planet, Piccolo decides to remain on earth - the Black Star Dragon Balls are too dangerous, and if he dies they will turn to stone, ensuring that nothing like this ever happens again. If Goku's reaction doesn't get the waterworks flowing, then either Piccolo and Gohan's last talk (which Piccolo concluded with "Take care, my son") and Gohan's anguished "PICCOLO-SAAAAAAN!" - surrounded by a completely oblivious crowd, no less - will.
In the English dub, Piccolo's final words to Gohan are "Goodbye...my friend...", which were the exact same words he said to Gohan, when he sacrificed himself to save Gohan against Nappa. Thinking about those two scenes will leave anyone in tears.
Definite example is the final episode of the whole series: "Farewell, Goku. Until We Meet Again.", being forced to leave Earth after saving it for the umpteenth time ... and after all that effort against that arc's Big Bad, with the majority of the cast not even aware that he has to leave them for a good century was really depressing.
This sequence is even more moving when you see the last scene, and the old woman Pan sees Goku, but he fades away walking through the crowd of people revealing that he was a spirit and had truly passed on for good.
The scene in the Baby saga when Goku gets beaten to a pulp by Baby and Pan breaks down and starts crying as everyone she loves is possessed or killed by Baby. Break the Cutie or what?
Buu: "You're Buu's best friend... forever and ever."
A scene in GT: It's right after Goku becomes a Super Saiyan 4 for the first time and goes to confront Baby. He finds Bulma with him and calls out to her. Unfortunately, she's already been turned into a Tuffle and shouts at Goku not to speak to her, calls him her enemy, and tells him that he will soon be killed, all the while with this distorted evil grin on her face. Yes, it's all the result of brainwashing, but when you think about it and realize how far back Goku and Bulma's friendship goes (The whole series started with them!), it is very sad to watch. The scene in question can be found here and starts at 5:22.