Mavis was originally a slave of Baroness Paula Von Gunther.She seized control of Paula's Nazi spy operation after Von Gunther's reformation. Cunning, deadly, and determined to take revenge on Paula and Wonder Woman, she stole the Amazon's invisible plane and used it for aerial sabotage, kidnapped Paula's daughter Gerta, and strapped Wonder Woman to a bomb before she was sent to Reformation Island, an Amazon penal colony (Wonder Woman #4).
After she discovered a dagger that emitted metal-eating acid from its tip, Mavis broke her bonds and escaped Reformation Island. Asserting control over Axis spy operations in the U.S., she established a covert headquarters at a Maine logging company. Wonder Woman discovered Mavis' location, but Mavis turned the tables and trapped Wonder Woman in her own magic lasso. Her control over Wonder Woman was disrupted when she miscalculated and removed Wonder Woman's bracelets. This incident triggered a berserker rage in the Amazon which resulted in demolition of the Nazi spy installation. Mavis was flung through a window during this process, which was ended only when Paula recaptured Wonder Woman with the magic lasso, ordered her to halt her destructive rampage and reforged her bracelets (Sensation #19, 1944).
Another, unrelated, Mavis Trent appeared in the DC Hawkman series in the sixties, beginning with Brave and the Bold #34. She served as an archaeologist, a naturalist, and a diorama artist at the Midway CityMuseum where Carter and Shiera Hall worked. Unknown to Mavis, Hawkman and Hawkwoman were married to one another, and not merely colleagues, which led her to flirt with Hawkman and provoked jealousy in Hawkwoman's case. Neither wore a wedding ring as it was not the custom on their native Thanagar (Shayera's earring served as an alternative).
Later, she changed her hair red in an obvious attempt to get Carter's attention. At one time, she discovers the Hawks' secret hideout within the museum. She found Hawkwoman's costume and decides to put it on, making her look remarkably like Hawkwoman (even Hawkman was fooled). Unfortunately, during The Shadow War of Hawkman, she was vaporized by the Wingmen of Thanagar who mistaken her for Shayera Hol. Her last (Pre-Crisis) appearance was in Hawkman Special #1, she inhabits Katar's dream while he was getting over with her recent death, along with the deaths of Fel Andar, the Gentleman Ghost and others.
Mavis appears as an exhibit coordinator of the Edwards Natural History Museum in Chicago. She was behind the newly established Thanagarian exhibit. Much like her previous incarnation, she occasionally flirts with Katar Hol, but he had feelings for Shayera Thal. Her current whereabouts are unknown as of now.