Rex the Wonder Dog is a fictional superhero dog in the DC Comics universe. Created in 1952 by Robert Kanigher of Wonder Woman fame and artist Alex Toth, Rex has sometimes been compared to Superman's dog Krypto, who was created three years later. While the two canine crime fighters do share some similarities, they are decidedly different.

Alexander Toth was an American cartoonist active from the 1940s through the 1980s. Toth's work began in the American comic book industry, but he is also known for his animation designs for Hanna-Barbera throughout the 1960s and 1970s. His work included Super Friends, Fantastic Four, Space Ghost, Sealab 2020, The Herculoids and Birdman. Toth's work has been resurrected in the late-night, adult-themed spin-offs on Cartoon Network’s late night sister channel Adult Swim: Space Ghost Coast to Coast, Sealab 2021 and Harvey Birdman, Attorney at Law.