| Year | Title | Role | Notes |
| 1975–1980; 2015 | Saturday Night Live | Various | Cast member (1975–1980) and a guest appearance on SNL 40th Anniversary Special 108 episodesNominated—Primetime Emmy Award for Individual Performance in a Variety or Music Program |
| 1977 | The Love Boat | Regina Parker | Episode: "The Captain's Captain/Romance Roulette/Hounded (A Dog's Life)" |
| What Really Happened to the Class of '65? | Ivy | Episode: "Class Hustler" |
| 1981 | Bob & Ray, Jane, Laraine, & Gilda | Herself | TV movie |
| 1982 | Candida | Prossie |
| Divorce Wars: A Love Story | Vickey Sturgess |
| 1983 | The Coneheads | Prymaat (voice) | TV short |
| 1984 | Bedrooms | Laura | TV movie |
| 1984–1989 | Kate & Allie | Allison 'Allie' Lowell | 122 episodesPrimetime Emmy Award for Outstanding Lead Actress in a Comedy Series (1984–1985)Nominated—Golden Globe Award for Best Actress – Television Series Musical or ComedyNominated—People's Choice Award for Favorite TV Performer (1984–1985)Nominated—Primetime Emmy Award for Outstanding Lead Actress in a Comedy Series |
| 1988 | American Playhouse | Lina McLaidlaw | Episode: "Suspicion" |
| 1988 | Maybe Baby | Julia Gilbert | TV movie |
| 1990 | Common Ground | Alice McGoff |
| Working It Out | Sarah Marshall | 13 episodes |
| 1994 | Dave's World | Anne | Episode: "Lost Weekend" |
| 1995 | Tad | Mary Todd Lincoln | TV movie |
| Mystery Dance | Susan Baker | Episode: "1.1" |
| 1996–2001 | 3rd Rock from the Sun | Dr. Mary Albright | 137 episodesSatellite Award for Best Actress – Television Series Musical or ComedyNominated—Satellite Award for Best Actress – Television Series Musical or ComedyNominated—Screen Actors Guild Award for Outstanding Performance by an Ensemble in a Comedy Series |
| 1998 | Hercules | Hippolyte (voice) | Episode: "Hercules and the Girdle of Hippolyte" |
| Recess | Mrs. Clemperer (voice) | Episode: "Wild Child" |
| 2000 | Catch a Falling Star | Fran | TV movie |
| 2003 | Cyberchase | Lady Ada Byron Lovelace (voice) | Episode: "Hugs and Witches" |
| Our Town | Mrs. Webb | TV movieNominated—Satellite Award for Best Supporting Actress – Series, Miniseries or Television Film |
| 2004 | The Librarian: Quest for the Spear | Charlene | TV movie |
| 2006 | Crumbs | Suzanne Crumb | 13 episodes |
| The Librarian: Return to King Solomon's Mines | Charlene | TV movie |
| 2007 | Nice Girls Don't Get the Corner Office | Joy |
| 2008 | In the Motherhood | Mom | Episode: "Mother Dearest" |
| The Librarian: Curse of the Judas Chalice | Charlene | TV movie |
| 2008–2009 | Gary Unmarried | Connie | 2 episodes |
| 2009 | Sherri | Margo/Paula's Mom | Episode: "Birth" |
| 2010 | The Women of SNL | Various/Prymaat Conehead/Weekend Update | TV movie; archive footage |
| Rex Is Not Your Lawyer | Unknown | Episode: "Pilot" |
| 2011 | The Oprah Winfrey Show | Herself (guest) | Episode: "Saturday Night Live Class Reunion" |
| 2012–2014 | Unforgettable | Joanne Webster | 34 episodes |
| 2014–2017 | The Librarians | Charlene | 5 episodes |
| 2015 | The Good Wife | Judge Farley | Episode: "Bond" |
| 2017 | Broad City | Margo | Episode: "Witches" |
| 2019–2021 | The Good Fight | Judge Pamela Farley | 3 episodes |
| 2020 | United We Fall | Sandy Ryan | 8 episodes |
| 2022 | The Conners | Doris Goldufski | Episode: "The Dog Days of Christmas" |
| 2023 | Bupkis | Marie LaRocca | Episode: "Do as I Say, Not as I do" |
| 2025 | The Residence | Nan Cox, mother-in-law to the POTUS | |