In television, Tallman worked on the soap opera, Generations. Later, she had guest-starring roles on Tales from the Dark Side, and the science fiction shows Star Trek: The Next Generation, Star Trek: Deep Space Nine and Star Trek: Voyager. Tallman played the character Lyta Alexander in the Babylon 5 series pilot, recurring in seasons two and three, and starring in seasons four and five. With fellow Carnegie Mellon alumnus George A. Romero, Tallman collaborated on several films, including Knightriders, Monkey Shines, and Creepshow 2 (in which Tallman performed stunts).
In 1990, Tallman starred as Barbara in the Savini-directed remake of the 1968 classic, Night of the Living Dead. She also played the Possessed Witch under heavy make-up in the cult classic Army of Darkness. In addition, she served as stunt double for Laurel Holloman, who portrayed vampire hunter Justine Cooper in an episode of Angel.
Tallman's recent acting credits include the psychological horror short, Jennifer Is Dead, the black comedy For Pete's Wake, and guest spots on Without a Trace and Castle. Tallman later appeared in the 2009 horror film Dead Air, and in InAlienable (2008) Tallman plays Dr Klein, a crony of the evil scientist