Wendy Harris, Marvin White and Wonder Dog are fictional characters from the 1973 American animated TV series Super Friends, based on the famous superheroes published by DC Comics. The series featured a lineup of DC's most popular characters, including Superman, Batman and Wonder Woman, but Hanna-Barbera, the show's producers, wanted to include young sidekick characters that the children in the audience could identify with. This led to the creation of Wendy, Marvin and their hero pet Wonder Dog, who appeared alongside their more famous friends. Because of the success of the Super Friends cartoon, a Super Friends comic book was also created, in which the trio made their first comics appearance.
Wendy, Marvin and Wonder Dog didn't have superpowers, so often they didn't add much to the story progression, and they were dropped after the show's first season. Wendy and Marvin were replaced in the 1977 series The All-New Super Friends Hour with the Wonder Twins -- extraterrestrial twins with the power to transform into animals and water. Wonder Dog's comedy relief role was filled by the Wonder Twins' pet monkey, Gleek.
Wendy's voice was played by Sherry Alberoni, and Marvin and Wonder Dog were voiced by Frank Welker.
The duo has been reintroduced in the Teen Titans comic book as the caretakers of Titans Tower, as twins Wendy and Marvin Harris. Wendy eventually became the protege of Barbara Gordon, while the latter was operating as Oracle, and adopted the codename Proxy. Stories published in this era also revealed that the twins were the children of the DC Comics supervillain Calculator.