Kraid

Kraid (, Kraid) is a recurring boss in the series. Kraid is a massive, high-ranked Space Pirate with three eyes and the ability to generate and fire spikes from his stomach and fingers.

Origin
Kraid is one of the major antagonists from the Metroid series, making his debut in the first game alongside Ridley and Mother Brain. In his original appearance, Kraid was depicted as a humanoid rhinoceros-like creature, although Super Metroid redesigned him as an enormous reptilian creature, which was retroactively featured in the first game's GBA remake Metroid: Zero Mission.

In Metroid and Zero Mission, Kraid is one of two Space Pirate bosses who must be hunted down and defeated by Samus Aran in order to access Tourian, the final area where Mother Brain and the eponymous s are located. Kraid's lair is located in the depths of Brinstar, and is also home to a false Kraid that is much weaker than the real boss. Unlike Super Smash Bros., Kraid is never fought in an area with lava until Dread, although he is fought in a room with pools of acid on either side of his platform in Metroid. In Zero Mission, defeating Kraid allows Samus to find the Speed Booster. Kraid also appears in the Monthly Magazine Z-published Metroid manga, based on his role in Zero Mission.

In Super Metroid, Kraid plays a similar role as before, now one of four Space Pirate bosses who must be defeated in order to access Tourian. Kraid can be found in a new Space Pirate base in lower Brinstar, where his chamber is guarded by Kihunters, Zebesians, and Mini-Kraid. Kraid rises from a thicket of brambles and thorns to challenge Samus, attacking with his claws and stomach spikes. Upon his demise, Kraid sinks into the ground, clearing the way for Samus to find the Varia Suit.

After 17 years of absence, Kraid returns as the second major boss in Metroid Dread. He has been forcibly restrained by the Mawkin Chozo in Cataris, the geothermal power plant of planet ZDR. Similar to Super Smash Bros., he is fought in a room with a pool of lava, and he strikes Samus's platform with his claw midway through the battle. His means of attack generally remain the same as in previous series, with the addition of new attacks such as fireballs from his mouth and a purple poison attack coming out of his stomach. Upon defeat, Kraid breaks free from his restraints but immediately sinks into the lava, making the way for Samus to find the Diffusion Beam. At the end of Metroid Dread, an X parasite merges with Raven Beak and becomes Raven Beak X, a hybrid of Kraid and Raven Beak, which implies that Kraid had been assimilated by the X after his defeat. Immediately afterward, Raven Beak X is obliterated by Samus's Hyper Beam, likewise eradicating the last remnants of Kraid.

Kraid was planned to appear in Metroid Prime as a boss wearing a metallic helmet to protect his vulnerable head, although this was scrapped due to time restraints. Outside of the Metroid series, Kraid has also appeared as a towering robot animatronic in the "Metroid Blast" attraction of Nintendo Land; much like in Super Smash Bros., this appearance has Kraid emerging from a pool of lava.

As a stage element
Kraid is a key factor of the Brinstar Depths stage, which is based on his lair in . Kraid rises from the lava in the background every fifteen seconds, roars, and then slashes at the stage, which causes it to rotate either clockwise (if Kraid slashes with his right hand) or counterclockwise (if Kraid slashes with his left hand). Since he remains entirely in the background, he cannot directly affect or be hit by the fighters. He also appears as a trophy, unlocked with the Brinstar Depths stage.

Sticker
Kraid simply appears as a sticker in Super Smash Bros. Brawl, as Brinstar Depths only returns in the form of its music track.

As a stage element
Kraid returns alongside the Brinstar Depths stage, playing the same role as before. His model has been updated with significantly higher detail, bringing him closer to his established canonical appearance in the Metroid series.

Spirit
Kraid is also a master spirit and is unlocked in Adventure Mode: World of Light, in a stamina battle against a Giant on Brinstar Depths' Ω form. As a master spirit, Kraid cannot normally be equipped by fighters; exclusively during this fight, he is classified as a Neutral type. Once unlocked, Kraid runs a Dojo where he teaches the Tank Style, which increases offense and defense but reduces move speed and jump.

The following is a list of quotes that Kraid can say when a player visits his dojo.
 * "ROAAAAAAAAAAAAAAAAAR! (That's probably a greeting.)"
 * "Gwoooh! Guruoo... (He's explaining what the style does.)"
 * "Grruurrr... (He seems to be waiting for you to choose.)"
 * "Gaaaaahhh! (That's a...happy noise?)"
 * "Ga-rurr... (That's basically "what now?")"
 * "Gurru... (He isn't listening. Quit training?)"
 * "Gy-aon! (That must be "come back soon!")"
 * "Guwaaa [number]SP GRAAAAH! (Likely the price of learning the style.)"
 * "Guuuuooon!! (He seems pleased.)"
 * "Gug yaaah! (See...you...later?)"

Trivia

 * As a Master Spirit, Kraid is given dialogue for the first time in a videogame; however, it consists entirely of roars and grunts. Translations are provided in parentheses, although these translations seem to be somewhat uncertain (often guessing what Kraid means or ending with a question mark) for added humor.