This native West Virginian first came to notice as an original cast member of Lanford Wilson's "Hot L Baltimore,” the award-winning Off-Broadway production which Norman Lear later produced as a series for the 1974-75 ABC-TV season. The show brought sexual innuendo and racy dialogue into the nation's living rooms, some of it courtesy of Ferrell's character, prostitute April Green. Despite some affiliates refusing to carry the show, ABC kept it on the air for four months before it was finally dropped due to lack of viewer interest. Ferrell remained in Los Angeles, where her often tart-tongued and bossy but always warm and earthy demeanor garnered her continuing employment in a slew of supporting character parts, including plenty of nurses and, for variety, the occasional doctor.

Making her theatrical film debut as a feisty programmer in Sidney Lumet's "Network" (1976), Ferrell shed her typically urban persona when she won her first and to date only starring role opposite Rip Torn in Richard Pearce's small-scale, beautifully acted gem about rural life, "Heartland" (1980). She appeared in the ensemble comedy romance "Mystic Pizza" (1988), and also served up a memorably hokey performance in Tim Burton's "Edward Scissorhands" (1989). Ferrell later acted in Tony Scott's "True Romance" and Oliver Stone's "Heaven and Earth" (1993) and left an impression on viewers as the busybody office manager who frequently clashed with Julia Roberts in "Erin Brockovich" (2000). That same year, she lent her typically earthy presence to the brief role of Ellen Barkin's high-spirited best friend in the otherwise mundane "Crime + Punishment in Suburbia.” The actress played a character named Mama Cass in the women's correctional facility telepic "Stranger Inside" (2001), followed by a supporting turn in the ABC TV movie "Oprah Winfrey Presents: Amy and Isabelle" (2001). Ferrell continued to appear in features with stints in "K-PAX" (2001), "Mr. Deeds" (2002) and the mockumentary "Surviving Eden" (2004).

Among Ferrell's many spots as a TV primetime series regular are roles on the popular seriocomic road adventure "B.J and the Bear" (NBC, 1978-81) and "L.A. Law" (NBC, 1991-92), for which she received an Emmy Award nomination. In many cases, Ferrell joined established series during their runs: for example, she was featured during the last two seasons of "Hearts Afire" (CBS, 1993-95) as a sharp-tongued psychiatrist who writes an advice column for the small-town paper which the protagonists publish. Later, she returned to the series grind as a diner owner in the short-lived ABC sitcom "Townies" (1996-97) and as the aunt of a teen whose best friend serves as his guardian spirit in "Teen Angel" (ABC, 1997-98). The actress was a guest star on several popular series, including "Buffy the Vampire Slayer," "Touched by an Angel," "JAG," "Friends," "Popular," "ER," "Sabrina the Teenage Witch," "Becker" and "Judging Amy," and she appeared on the short-lived drama "Push Nevada" (ABC, 2002). The actress delivered another memorably tart-tongued creation in her recurring role as Berta, Charlie Sheen's sardonic housekeeper on the hit sitcom "Two and a Half Men" (CBS, 2003- ). Ferrell’s winning portrayal of the sassy, blue-collared Berta twice earned her Emmy nods – first in 2005, then again in 2007 – for Outstanding Supporting Actress in a Comedy Series.