"Last Train to Doomsday" is the fifth episode of the second season of Thundarr the Barbarian. It originally aired on ABC on October 10, 1981.
Thundarr, Ookla, and Ariel are in pursuit of a mummy-like Janus after he and a race of hawk mutants attack villages and the train route of Tye (the former swamp urchin from the second episode of the first season, "Harvest of Doom"). The group is in for a surprise when it turns out Janus is actually Gemini (the two-faced wizard from the very first episode, "Secret of the Black Pearl") in disguise seeking revenge on Thundarr. Tye, from "Harvest of Doom", returns as well.