Born and raised in Portland, Oregon, Janet Ellenmarie Penner began acting in local theater productions before making her feature film debut in local filmmaker Don Gronquist's grisly slasher Unhinged (1982)], in which she portrayed the gender-bending killer Marion Penrose. The film received notoriety after it was banned in the United Kingdom and deemed a "video nasty."

In the intervening years, Penner, a graduate of the University of Portland, continued to appear in occasional locally-filmed features, including the supernatural thriller The Haunting of Sarah Hardy (1989), and the Walt Disney live-action film Homeward Bound: The Incredible Journey (1993). She has also appeared on television, in an episode of the series Leverage (2008).

In addition to her film credits, Penner has had a long career in repertory theater, having starred in numerous stage productions with the Portland Civic Theatre, the Artists Repertory Theatre, the Oregon Children's Theater, and the Willamette Repertory Theatre.