As an arcade Shoot 'em Up series, Gradius has its fair share of bosses of outstanding difficulty. Not helped by this is that in most games, dying to a boss takes you back to right before the boss, with barely any powerup items to re-arm yourself with.
Special note regarding this page: Normally, Final Bosses normally do not qualify for this trope. However, a quote from the main trope page: "Final Boss and Wake-Up Call Boss cannot be That One Boss without being overly hard by their standards." As the standard for final bosses in this game is "defenseless", and it's easier to count how many bosses do fight back, difficult Gradius final bosses can qualify for this trope. Wake Up Call Bosses are still not allowed unless they really stick out, however.
- Starting with Gradius II, nearly every game has one boss in the "enemy base" stage (usually the last or second-to-last stage) where a giant screen-filling mech appears and you must maneuver your way around it, while regular enemies continue to harass you and become even deadlier due to your limited breathing room. Oh, and several of these bosses are invincible (Club in non-NES versions of Gradius II, Shadow Gear in Gradius III AC, Sol in Gradius Gaiden, to name a few), meaning that the only way out is to survive until it leaves.
Salamander / Life Force
- In the arcade versions, the Stage 4 boss is just utter nonsense. It's a trio of cores that shoot out bouncing bullets that quickly fill the screen and can overwhelm any player. Thankfully, ports of this game that aren't arcade-perfect tone this boss down.
Gradius II -GOFER no Yabou-
- Covered Core from II fires missiles willy-nilly while covering (hence its name) its core with 3 layers of fast-moving shells. While this boss doesn't actually comes back in V, it has an even stronger variant that not only has multiple spinning cores, but also fires lasers whenever it spins its shields and guns to go along with the missiles, some of which will explode and create a spreadshot.
Gradius III -Densetsu kara Shinwa e-The title literally translates to "From Legend to Myth", and you pretty much have to be a "myth" to take on bosses from what may well be the hardest game in the series.
- Big Core MK. III is one of the most infamous bosses in Gradius III Arcade, itself considered one of the hardest games in the series. First of all, it fires 2 large containment lasers followed by fast reflecting lasers, limiting movement. Destroying the 2 front cores is when things get really bad; Now, the reflecting lasers are swapped with an extremely fast Beam Spam. Many a life has been lost on this attack. Trying to hide on the top or bottom? It'll either try to ram you into either itself or the containment lasers, forcing you back to the center, or it'll move to the left and fire 7 lasers behind itself. This boss gets not one, but two rematches in Gradius IV and Gradius V respectively.
- Vaif, the Stage 5 Moai boss in Gradius III Arcade, doesn't fare much better in this regard. The boss itself is a set of 6 Moai heads, but the Moai also shoot out tiny Moai that expand when hit limiting your movement, and the mouths are also placed very awkwardly for your weapons to hit them. So in short, we have a boss with several almost impossible to hit weakpoints that attacks by spawning miniature Demonic Spiders. Without upgraded weapons or Options you're best off just not firing at all and letting the boss time out.
- While Wyvern is a cakewalk to tackle, the arcade version of Vulture Dragon can be pretty challenging, thanks to its surprisingly fast movement speed, fireballs that explode into clusters of smaller fireballs, and having two tanky weak-points (both heads at each end) that are blocked by its long serpentine body, essentially making this boss a Lightning Bruiser. The SNES version of Vulture Dragon may be toned down from its arcade counterpart, but upon defeat, its segments can kill the Vic Viper if the player isn't careful.
- Stage 10 features Disrupt, a Cores-and-Turrets Boss but with parts of the floor and ceiling sliding up and down to restrict your movement, followed right after by Shadow Gear, yet another "survive this indestructible boss until time runs out" fight, while Duckers walk up and down to harass you. It's an eight-legged mech that often moves four legs at a time and has a severe case of Hitbox Dissonance, sometimes getting you killed when no part of its body is visibly touching you. There's even a crippling bug, albeit a rare one, where Shadow Gear's hitboxes inexplicably fill the screen and kill you with no way to counteract it! But apparently, just facing each of them isn't enough, because there is no checkpoint between Disrupt and the Shadow Gear, so if you die at any point in this set, you have to fight Disrupt all over again!
Gradius GaidenGradius Gaiden is widely regarded as one of the easiest Gradius games, but that only makes the hard bosses stand out even more.
- In the second loop of Gradius Gaiden, Deltatry, the fourth boss of the Stage 8 Boss Bonanza, not only fires its usual red flak spam that can at least be shot down, but also fires blue flak that can't be destroyed and blocks attacks other than the Lord British's Disruptor laser. This makes for a longer and more unsafe fight.
- The exclusive final Stage 8 Boss Bonanza boss only seen on loops 2 or higher, Heaven's Gate, is even worse. It's the Beam Spam of Big Core MK. II, combined with the containment lasers of Big Core MK. III (minus the reflecting lasers). Oh, and it shoots suicide bullets upon defeat.
Gradius IV -Fukkatsu-
- Belial, the Womb Level boss, is a souped-up version of Brain Golem. Its arms aim at the Vic Viper's vertical position and fire Frickin' Laser Beams all over the place, thanks to its own Attack Drones. Upon defeat, a Zelos Force comes out of Belial and fires lasers all over the screen while reducing your maneuvering space with its massive size.
- Rolling Core, the game's 7th stage boss, already That One Level in itself due to being a high speed stage. The developers have the nerve to throw a boss with small laser guns filling all the empty space down the flat side facing you, the "donut hole" core aims independantly of the outer shell, so it fires around 10 lasers in one direction and another 4-6 in another... and every time you think you've got its pattern figured out...it throws something new at you, like turning the core sideways and blasting you with a no "other" warning laser blast. And then Treasure has the gall to bring this boss back for a rematch in a Boss Rush in Gradius V.
- The first example is Blaster Cannon Core, the boss of Stage 5, the asteroid base. What makes this boss hard is the exact navigation the pilot has to go through; the meteor field for the boss is much thicker than the rest of the stage (as if it wasn't thick enough to begin with), and when the blaster first spirals onto the screen, it's leaving behind a trail of mines that produce two shockwaves of bullets. You CAN destroy the mines before they explode and no bullets will come out of them. Once the rock flow changes and the Vic Viper can attack the core, this machine spams Bullet Hell on you and you have to navigate the asteroids (the blaster's superlasers can destroy the rocks, but make sure you're in the center of the vertical axis). It's also the current page image of that trope's Shoot 'Em Up page.
- The second is Keeper's Core, the first of two bosses met at the end of Stage 7. After a plethora of enemies with powerups, the pre-boss area requires precise navigation through a minefield with Ducker turrets firing at you. Once the gunwall forms, it has two phases; the first phase, in addition to both the regular bullets from six smaller guns (which can be destroyed, but it will be replaced in 5 seconds) and the plasma shots from three big guns (which you need to destroy) will fill the room, plus there's a gravity field that will pull the Vic Viper towards the ceiling or floor. Plus, more Duckers keep walking in. This part is infernally difficult, but if the pilot can survive, you then have to shoot the cores while the wall is laying lasers; rolling balls coming in to ram you from behind will block these lasers (the smaller guns will keep firing and the wall can charge you, too.)
- The mid-boss of this stage, Beacon from Gradius III SNES, isn't much better; this one shoots lasers that bounce off the walls and in your general direction while it occasionally fires containment lasers. Plus it can drop bombs and alter the hallway to make it smaller and then crooked (this second version has it firing Bullet Hell bullets at you. While it is advised to destroy this machine, it's not required; after several rounds of these attacks, the Beacon bounces off and the second part of the stage starts up anyway.
- Ogre Shield of Stage 4. It fires extremely huge Frickin' Laser Beams and you have hard time to avoid them.
- Central Server, the final boss. While the main console is a Zero-Effort Boss, it launches the diamonds to warp around, trying to attack the player. Beat it correctly and it can become Breather Boss.
- Doom, the Final Boss of Salamander 2. Yes, he is a Final Boss. However, it's extremely rare for a Gradius final boss to not be a Zero-Effort Boss; on the contrary, Doom throws Bullet Hell of all kinds at you and is the hardest boss in the game.
- Venom, from Nemesis 2, also a non-pushover Final Boss. His Lightning Gun attack is hard to predict and dodge, unless the player knows about the safe spot, which is somewhere in the middle.
- Gradius Galaxies/Generations/Advance has Bolboros, which looks suspiciously similar to Rolling Core. The smaller ship attacks like Big Core MK 1, and the larger ship simply fires two long lasers. However, destroying either ships will make the other ship more aggressive. The smaller ship fires streams of bubbles, while the larger ship moves closer to your fighter.