Rexes are dinosaur-like dragons who inhabit Dinosaur Land and other places, first appearing in Super Mario World. Their English name is the Latin word for "king", and is likely derived from the predatory dinosaur Tyrannosaurus rex. They are indigo-to-violet with a nasal horn, fangs, and small dragon wings, though they are flightless. They also wear big red shoes, similar to Yoshi. A recurring trait with all Rexes are their compressible bodies, as their stature becomes flatter when jumped upon.
Super Mario World
Rexes are rare enemies in Super Mario World who act like Goombas, simply walking in Mario's direction. They are usually found in small groups. In order to defeat a Rex, Mario needs to jump on it twice. After being jumped on once, a Rex simply becomes flattened and moves slightly quicker. A Spin Jump can destroy them in one hit, as will shooting a fireball, hitting it with a cape or running into it while using a Starman. Rexes can also be eaten by Yoshi. Rexes can be found in Yoshi's Island 1, Chocolate Island 2 and Awesome.
Super Mario World television series
Rexes, referred to by the generic term Dinosaurs, make several appearances in the Super Mario World animated series. The Rexes of Super Mario World come in different colors, such as green, red and yellow. Unlike in the game, they bear at least some resemblance to actual dinosaurs, they lack shoes, have clawed hands and feet, and their lower jaw now has different coloring from their belly. Some Rexes have bird-like wings, and others have second nasal horns.
Rexes first appeared in the episode "Send in the Clown", where several are shown disguised as clowns in King Koopa's "Koopaling Bros. Circus". After several misadventures in their circus act, that the clowns are accidentally revealed to be Rexes, who, upon tearing off their costumes, begin to herd all the circus audience members into a large pit. In this episode, they more closely resemble their in-game depiction.
In "King Scoopa Koopa", several multicolored Rexes are shown to be working as employees at King Koopa's fast food stand. After it is revealed that King Koopa had planned on mutating the inhabitants of Dome City into Chickadactyls - which he plans on deep frying and selling to Rexes - King Koopa sends several Rexes to capture Mario and Princess Toadstool. Mario and Princess Toadstool escape using the Star Path, and return later to defeat the Rexes using a cape. The Rexes that were not defeated by Cape Mario later escaped down a Warp Tube, along with King Koopa.
In the episode "Born to Ride", two Rex bikers named Duke and Rockman appear. Duke and Rockman, along with their ally, Lulu, attempted to manipulate Yoshi into capturing Mario and Luigi for them, only to be beaten in the end.
In a later episode entitled "Rock TV", two other Rex characters named the Tyrannosaurus Twins appear. The Tyrannosaurus Twins are wrestlers, and pummeled Mario and Luigi for sometime, though they were eventually defeated by Cape Mario.
Nintendo Adventure Books
A Rex has appeared in volume 3 of Super Mario-Kun. Yoshi invites Mario and Luigi to meet his friend, a Rex who decided to turn against Bowser. He captures the Mario Bros. and attacks Yoshi, thinking they're working for Bowser. After the Mario Bros. demand an explanation, Yoshi convinces the Rex that he is a friend by showing his long tongue. The four then go into Rex's house, where Yoshi demands food, and Rex promises to cook. However, a Magikoopa and a Koopa Troopa called "Number 3" then use the kamemeka (an enchanted Koopa Shell) to brainwash Rex. Rex then makes a poisoned soup in attempt to defeat Mario, which Yoshi quickly digests. Rex then smugly asks if Yoshi enjoys the poisoned meal, which shocks Mario. After some groaning, however, Yoshi claims it was "delicious". Mario calls Yoshi an idiot, pointing out Rex's intention to kill them, but Yoshi denies it, saying that Rex is only a harmless friend.
Furious that he did not succeed, Rex then uses a flamethrower to burn Mario and Yoshi, while Luigi dodges in time. The Magikoopa then uses his power to make Rex grow. Rex attempts to stomp on Mario, but Mario steals his shoe and tries to use it as a Goomba's Shoe, only to be overpowered by its odor. Yoshi then tries and fails to make Rex remember good memories. Meanwhile, the Magikoopa decides it is time to finish off Mario and his friends, and gives the Rex bigger wings, transforming him into a Super Rex. During a chase, however, Mario finds a switch and turns it on, letting blocks fall on the Rex's head and removing the magical Koopa Shell. After the kamamaka falls off, Rex and the others put the kamemeka on The Magikoopa instead, and Mario forces The Magikoopa to dance under it, thus ending the chapter.
Super Mario Adventures
Rexes also appear in the Super Mario Adventures comic, where several of them are seen among the attendees at Bowser's wedding to a brainwashed Princess Toadstool. Later on, after Mario, Luigi, Yoshi and a herd of Yoshis crashed Bowser's wedding, a lone Rex is seen among the creatures trying to defeat the Yoshis, only to be trampled by them.
Super Mario Bros. film
Mario & Wario
Super Mario World: Mario to Yoshi no Bōken Land
Rexes appear in the interactive anime video Super Mario World: Mario to Yoshi no Bōken Land. When the Mario Bros. discover Yoshi's egg on Yoshi's Island, Luigi prompts the player to answer which character is inside, with a Rex being one of the incorrect answers. When leaving the island, the Mario Bros. and Yoshi are confronted by Iggy Koopa alongside Koopa Troopas, Chargin' Chucks and Rexes. Mario then prompts the player to answer which enemies there are more of, with five Rexes being the incorrect answer (the correct answer being six Koopa Troopas).
Mario & Luigi series
Mario & Luigi: Superstar Saga / Mario & Luigi: Superstar Saga + Bowser's Minions
Rexes reappear in Mario & Luigi: Superstar Saga as enemies located on Hoohoo Mountain, past the Hoohooros Gate. They do not appear on the overworld, and only appear in battle alongside Dry Bones or Beanies. Like in Super Mario World, Rexes attack Mario or Luigi by charging into them, and can be be flattened by jumping on them. When they are at their full size, the Rexes' attacks cannot be dodged or countered as they are too tall to jump over. When flattened, the player can then counterattack the Rex without getting hit. Jumping on a Rex a second time flattens it even more, but does not decrease in height any further after jumping on it more than twice. Rexes drop different items if they were defeated normally (with Hammer attacks or a strong enough attack to defeat it in one hit) or while flattened: they drop Syrups when defeated without being flattened, and either Mushrooms or 1-Up Mushrooms when flattened (they drop Green Peppers instead of 1-Up Mushrooms in the Japanese version). Rexes are healed with fire-based attacks, but take normal damage from thunder attacks.
Rexes reappear in Mario & Luigi: Superstar Saga + Bowser's Minions, with the same role as in the original game, after a twelve-year absence. They are much larger than in the original game, but Mario and Luigi can now counterattack them when they are at their full size. Rexes make high-pitched grunts when jumped on. They also appear as enemies in Minion Quest: The Search for Bowser. Rexes are Melee troopers, and attack by charging into opponents. Their Special Skill, Mega Tackle, allows them to charge quickly into an opponent, inflicting more damage than a regular charge. When a Rex is a captain on the enemy team, it does not say anything when using a Captain Command, as indicated by an ellipses in its text box.
Mario & Luigi: Partners in Time
Though normal Rexes do not appear in Mario & Luigi: Partners in Time, a Shroob-like form of them, called Shroob Rex, appears in the game. Shroob Rexes are encountered in the Shroob Castle and have a different, slightly larger appearance with pincers for hands, dark magenta scales, and glowing red eyes. They also possess the ability to breath fire.
Super Princess Peach
Normal Rexes appear in Super Princess Peach, first appearing in Fury Volcano 4-1. Their behavior is mostly unchanged Super Mario World. When jumped on, they shrink and can be defeated by another stomp, though they can be defeated instantly by any other attack. Rexes who have been affected by the Sad Vibe, called Sad Rexes, also appear. Sad Rexes will not move until Princess Peach approaches, in which case they will charge at her. Jumping on them will turn them into regular flattened Rexes, however, and they can be defeated using the same methods as normal counterpart.
A Rex appears as a sewing design in Mario Family.
In Mario's FUNdamentals, Rexes appear as a playing card when the player plays Go Fish with Mario.
In the Super Mario Mash-Up Pack in Minecraft, Zombie Pigmen are replaced by Rexes.
Physical description and traits
Rexes are dinosaur-like dragons with single nasal horns, large fangs, and small dragon wings. They have purplish bodies with an orange pattern that covers their bottom jaw and runs down from the sides of their mouths to underneath their bellies (there is no known orange pattern on the bottom of their tails). The main color of the Rexes' bodies varies between games and official artwork: the official artwork for Super Mario World depicts them having dark blue bodies, but in games the color is often violet or purple (with the exception of Super Princess Peach which is a solid blue). There are three rib patterns on the orange part of their bellies. Their tails have two small spines down the center. Rexes wear big red shoes similar to Yoshis, but are more simplistic in design and have smaller beige soles underneath. Rexes have no nostrils and the backs of their heads do not have any distinguishing traits.
Rexes have small wings, but cannot fly. The wings' membranes are often red and have three "fingers", and slightly thick "arms". In official artwork, the color of the wings' arms is a deep orange, and the membranes the same color as the Rex's belly. Starting from Mario & Luigi: Superstar Saga, the color the wings' arms match the color the Rex's body, and the membranes are red, matching the color of their shoes.
The depiction of the Rexes' eyes between artwork and games vary between always closed or with small pupils when open. In Super Mario World, Mario & Wario, Super Princess Peach, and the Super Mario Mash-Up Pack in Minecraft, their eyes are open, and in the original Mario & Luigi: Superstar Saga their pupils can be seen when they're hit. In most other games or artwork, their eyes are shut. A variant of the Rex, the Shroob Rex, are depicted with open eyes.
In the games, Rexes are taller than the Mario Bros. while even in Super form, and are even larger in Mario & Luigi: Superstar Saga + Bowser's Minions. Their size is used as a gameplay mechanic in the Mario & Luigi games where they are too tall for the player to jump over when dodging or counterattacking them while at their full size (regular Rexes in Mario & Luigi: Superstar Saga, and Shroob Rexes in Mario & Luigi: Partners in Time), and must be shrunken down to counterattack them safely. The Rexes in Super Princess Peach are smaller however, standing slightly shorter than Princess Peach herself.
A trait that Rexes have in games are their compressive bodies, being shrunken down when jumped on (similar to the Mario Bros. shrinking when powering down from their Super forms). This allows them to withstand single jump attacks and move quicker while in this flattened state (they can still be defeated instantly by any other attack, however). In the Mario & Luigi games, Rexes can be flattened two times with jump attacks (the second time flatter than the last) and the player can safely counterattack or dodge their attacks. In the Minion Quest: The Search for Bowser mode in Mario & Luigi: Superstar Saga + Bowser's Minions, however, Rexes do not shrink when attacked by the player's troopers that attack from above. The Rexes' body compression trait is also possessed by Morty Moles from Super Mario 3D Land.
While Shroob Rexes have the ability to breath fire, it is unknown if regular Rexes can do so. Nevertheless, Rexes seem to have some affinity to fire as they can absorb fire damage in both versions of Mario & Luigi: Superstar Saga and can only be encountered in the stages of Fury Volcano in Super Princess Peach.
Super Mario World / Super Mario World: Super Mario Advance 2
It's easy to vex Rex. Stomp once to crunch him like an accordion and twice to get rid of him for good. A Spin Jump takes him out in one step.
Mario & Luigi: Superstar Saga / Mario & Luigi: Superstar Saga + Bowser's Minions
Super Princess Peach
Glossary: A dinosaur-like enemy. Flip it with two stomps.
Names in other languages