One of Sunshine's star pupils, Rex King is from the United States. His special attack is called the "Jurassic Hand" with which his hand becomes a dinosaur hand (which later became fossilised due to the Spinning Toe Hold plus the Texas Clover Hold wearing out the skin). He is weak to cold, including cold tones and humour, and ultimately defeated by Terry the Kid.
Rex King can first be seen in disguise, where he is introduced alongside Check Mate. He appears on a large screen from Osaka, where he has defeated Gorgeousman and murdered Barbarian.  He later captures Terry the Kid, who breaks into the stadium early to challenge them, on behalf of orders given by Sunshine.  He goes on to release Terry from his bonds at noon, when the battle commences, and Kinniku Mantaro arrives to referee the match (as blackmailed by Sunshine). The battle initially goes in Rex's favour, as Mantaro takes a strict approach and rules often against the Kid. 
It should be noted that Mantaro (acting as the referee in Rex's match with Terry) counted the teeth of the Jurassic Hand as claws, and so not against all rules against biting your opponent (although he was actually blackmailed by Sunshine to bend the rules to Rex's advantage, so it may not actually be true). 
Rex misses a key attack when Mantaro defends Terry, at which point Sunshine steps into the ring and receives a yellow card, and this marks a steep change in how Mantaro referees the match.  Terry manages to rip the skin from Rex's Tryanno-Claw, which is changed to fossilisation in the anime, and temporarily regains the upper-hand after he injures himself to escape an attack.  It as at this point that Mantaro makes a cold joke, which injures Rex King, and the Kid works out that coldness is the weakness with which he can win the match, as dinosaurs were made extinct from the cold.  He is given earplugs by Sunshine, but the Kid manages to break the air-conditioning unit and freezes Rex King in that manner. 
While at Mantaro's house one day, Kid uncovers a letter from Meat Alexandria, who has gone to commit reconnaissance on the d.M.p, and - worried - he forces Mantaro to go look for Meat, who has been missing for some time.  They break into the d.M.p headquarters with Gazelleman, but are captured and tied up. Kid then breaks free and runs into a ring where Rex King waits for an opponent to fight.  Kid proceeds to attack Rex King, so that Mantaro can continue. 
Rex King attacks at first with a Western Lariat, but Kid counters with an Arm Bar. Rex King shows no fear, but instead uses his Jurassic Hand, and - after biting down on Kid's shoulder - he follows with a Dinosaur Back-Breaker. When Mantaro makes a joke, this leads to Rex King being literally frozen for a few seconds. Kid pleads with Mantaro to keep making bad jokes, sensing this is Rex King's weakness, as Rex King is a dinosaur and dinosaurs were wiped out in the ice age. This soon freezes Rex King whole, and allows Terry the Kid to perform a Sleeper Hold Suplex. This kills Rex King and shatters him into pieces. 
- Rex King primary technique. His hand transforms into a dinosaur head, and attacks with it.
- Smash his opponent with both feets
Skeleton Brash Jaw
- With his skeleton hand, bites his opponent in a brutal way
- Uses his tail as a whip
- Gives a powerful kick to his opponent
Kill the Half
- Another of his primary techinque. Catch his opponents with his Jurassic Hand and his tail, spliting the body in two.
- d.M.p Nightmares No. 1
- Night Watchmen No. 2 (V-Jump manga only)
Win/Loss Record (Singles)
Win/Loss Record (Tag)
- (w/Check Mate)
- 0 Barbarian & Gorgeousman
- Submitted by: Toru Nakahama (23) OF Osaka & Takashi Hama (27) of Osaka. (they originally sent in two different submissions, the author combined aspects of both)
- In the 4Kids dub, he doesn't care about his head, stating that to him it merely holds his brain (which can apparently be pushed into his torso without much damage) and that his Jurassic Hand is the head that Terry the Kid had to worry about