Clayface is a mutated being whose body has been transformed from flesh to clay. Capable of molding himself into any shape or size due to the clay-like nature of his body, Clayface has inspired other similarly-transformed beings to take up his name; as a group they are known as The Mudpack.
Basil Karlo was an actor who was driven insane when he heard that a remake of the classic horror film he had starred in, The Terror, would be shot without him acting in the film. Donning the mask of the film's villain, Clayface, he began killing the actors playing characters in the film in the order and way they died in the film. In spite multiple attempts, he was frequently foiled by Batman and Robin.
Following the appearance of four other "Clayfaces", Karlo proposes an alliance between all living Clayfaces to kill Batman, calling themselves "The Mudpack". Even though the Mud Pack was defeated, Karlo injects himself with samples from Clayface (Preston Payne) and Clayface (Sondra Fuller), and becomes the self-declared "Ultimate" Clayface.
Following another defeat at the hands of Batman, Karlo sinks into the Earth's crust and gains additional crystals in his body that endow him with greater powers. Escaping from the Earth when Gotham City was destroyed by an earthquake, he captures Poison Ivy in Robinson Park and enslaves her and the children she had adopted for the majority of the city's No Man's Land.
Since his defeat, once again by Batman and Robin, he has resurfaced as a member of the Secret Society of Super Villains.
In the alternate timeline where thanks to the efforts of Lex Luthor, Brainiac is in the process of subjugating the planet, Eclipso, the Trickster, Weather Wizard and Clayface are employed by Luthor to attack the small group of collective heroes and villains he had gathered to fight against Brainiac in a scheme to gain their trust by arriving to thwart the villains’ attack. After the scheme is successful and the collective departs, Luthor frees and vaporizes the four villains.
- Clayface is one of the possible bosses in the Turf War: Team Joker duo of the Riddled with Crime episode.
- Clayface is one of the random bounties in the Amusement Mile's Gang War (Bounty: Joker & Riddler Allies / Wanted: Joker & Riddler Allies).
- Clayface is part of the Wanted: Clayface Bounty for heroes.
- Clayface attacks the Gotham S.C.U. building and the player had to activate a containment unit to trap Clayface.
- Clayface is the second boss you have to fight in Gotham Subway Duo (after Bane or Hush depending on the route Two-Face picks). During the fight he will either take the form and power of Batman and Robin or Joker and Harley Quinn.
- Clayface is being held captive in the Gotham S.C.U. building The Joker asks you to infiltrate. Release him and he will assist with defeating all enemies remaining in the building.
- Clayface first appeared in Detective Comics #40 (June 1940)
- Clayface is voiced by Benjamin Jansen.
- A movie buff, Batman creator Bob Kane stated that Clayface was partially inspired by the Lon Chaney, Sr. version of The Phantom of the Opera and that the name of the character came from Boris Karloff and Basil Rathbone.
- Clayface once attempted to absorb Wonder Woman, who herself was created from clay, to become even more powerful. However, he was defeated by the combined might of the Amazing Amazon and Donna Troy.