Fenn's first high-profile mainstream credit was as the car accident victim wandering around with a windshield through her head in Lynch's "Wild at Heart" (1990). She was especially fine as Forest Whitaker's intended victim in "Diary of a Hitman" (1991), the directorial debut of her beloved acting teacher Roy London. "Ruby" (1992) cast her as a small-town stripper involved with Danny Aiello's Jack Ruby and the J.F.K. assassination conspiracy, and she appeared in Gary Sinise's remake of "Of Mice and Men (1992) as Curley's sexy wife, the object of John Malkovich's lumbering affections. Fenn followed with the romantic comedy "Three of Hearts" (1993), playing the woman who goes straight in a bisexual love triangle with William Baldwin and Kelly Lynch. She was surprisingly credible as the love object cut down to size in David Lynch's daughter Jennifer's controversial directing debut, "Boxing Helena" (also 1993), a role originally intended for Kim Basinger. She also acted that year in Carl Reiner's misfired parody of erotic thrillers, "Fatal Instinct", perhaps losing out to Sean Young in the battle of the femme fatales.
Television provided Fenn her best opportunities throughout the rest of the decade. She starred opposite Jamey Sheridan in the Waltonesque "Spring Awakening" (CBS, 1994), adapted from a Willa Cather story, and through the miracle of special effects got to act opposite Humphrey Bogart in a 1995 episode of HBO's "Tales from the Crypt". That year also saw her portray a living legend in "Liz: The Elizabeth Taylor Story", an unauthorized NBC miniseries made despite Taylor's objections. Fenn fought for integrity in her characterization of the great star, in lieu of focusing on the trashier aspects of the performer's life, and has heard through a source close to both actresses that Taylor approved of her interpretation. The CBS miniseries "A Season in Purgatory" (1996) offered her as a melancholy rich girl, but it was her return to series TV as the star of Showtime's black comedy "Rude Awakening" (1998- ) that allowed her to shine. As the habitually self-destructive former primetime soap opera star with a knack for making the wrong choice at every given opportunity, Fenn was at the center of its unctuously over-the-top swirl of addiction, sex and dysfunction.