Single parents in a sitcom

Tony on Who's the Boss?
Danny on Full House
Nick on Blossom
Jesse on Jesse
Ganeva on Hangin' With Mr. Cooper
Phil on Differnt Strokes
Micheal and Joey on My two Dads

Elaine on Taxi.

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Andrew Carden

Bill Bixby on The Courtship of Eddies Father,Andy Griffith- The Andy Griffith Show, Lucille Ball - Lucy Show and Here's Lucy, Brian Keith- Family Affair, Brian Kelly- Flipper, Richard Long- Nanny and the Professor, Barbara Stanwyck- Big Valley,Doris Day- Doris Day Show, Linda Lavin- Alice, Bea Benaderet -Petticoat Junction,Buddy Ebsen- Beverly Hillbillies.

Beverly Ann (FoL)
Julia (Julia)
Edie (Room for Two)
Deloeres and Kathy (Getting By)

Ross and Rachel on FRIENDS
Steve and Miranda on Sex and the City
Shirley Partridge on the Partridge Family
Ann Romano from One Day at a Time
Alice Hyatt Alice
Alan Harper Two and a Half Men
Jack McFarland Will and Grace
Mitch on Baywatch

Merrill Stubbing - The Love Boat
Vivian Bagley - The Lucy Show
Angela Bower - Who's The Boss
Julia Baker - Julia
Margaret MacDonald - The Bob Cummings Show
Mary Jo Shively - Designing Women
Frank DeFazio - Laverne and Shirley
Fred McConnell - Mork and Mindy
Bill Davis - Family Affair
Mabel Thomas - What's Happening
Fred Sanford - Sanford and Son
Claire Roman - Brotherly Love

Sam Jones (Ken Berry) - The Andy Griffith Show and Mayberry RFD
Steve Douglas (Fred MacMurray) - My Three Sons
Barbara Harper (Beverly Garland) - My Three Sons (before she married Steve Douglas)
Lorelai Brown (Pamela Britton) - My Favorite Martian
Carla Tortelli (Rhea Perlman) - Cheers

And also I believe -

Howard Borden (Bill Daily) - The Bob Newhart Show
Carol Traynor (Adrienne Barbeau) - Maude
Phyllis Lindstrom (Cloris Leachman) - Phyllis and The Mary Tyler Moore Show

And I think Fonzie's mom on Happy Days qualified as a single parent. There were lots of shows where a widow or widower was the parent of a grown character.

Karen Roe-One Tree Hill
Seely Boothe-Bones

Kate and Allie
Gov. Gatling on Benson
Teresa Arcola (Chachi's mom) on Happy Days until she married Al
Michael Hogan on Hogan Family after Valerie died
Gloria Stivic on Gloria

Carl Kanisky (Dolph Sweet) - Gimme a Break!

Edward Stratton III (Joel Higgins) - Silver Spoons (until he married Kate later on)

Eloise "Mama" Curtis (Theresa Merritt) - That's My Mama!

Florida Evans (Esther Rolle) - Good Times (after James died)

Grace Kelly (Brett Butler) - Grace Under Fire

Harry Weston (Richard Mulligan) - Empty Nest

Ned Flanders (Harry Shearer) - The Simpsons (after Maude died)

Rachel Crawford (Telma Hopkins) - Family Matters




Non-sitcoms:

Ben Cartwright (Lorne Greene) - Bonanza

Ben Matlock (Andy Griffith) - Matlock

Kate Bradley - Petticoat Junction
Steve Douglas - My Three Sons
Shirley Partridge - The Partridge Family
Lucy Carmichael -The Lucy Show

Lilith Sternin Crane, Frasier Crane, and Roz Doyle on Frasier (Martin Crane too)
Hayden Fox (Craig T. Nelson) on Coach
Ashley Pfister (Linda Purl) on Happy Days


Non-sitcom: Lucas McCain (Chuck Conners) on The Rifleman
Laura Dayton (Kathie Browne) on Bonanza