Main character by episode

[sm95fan]

Season 4:

Archie's Night Out: Archie, Barney, Mr. VanR
Gary's Ex: Gary, Billie
The Eyewitnesses: Jose, Raoul
Double Date: Stephanie, Billie
From the Waldorf to Astoria: Jose
Stay Out of My Briefs: Gary, Billie
Break a Leg, Stephanie: Stephanie
Archie Gets a Head: Archie
Barney Gets Laid Off: Barney
Marriage on the Rocks: Harry
Father Christmas: Billie, Archie, Stephanie, Fred Bunker
Teacher's Pet: Billie, Gary
Captain Video: Barney
The Promotion: Gary
Three Women: Stephanie
Relief Bartender: Archie, Pat McBride
The Red Herring: Mr. VanR, Archie
The Boys' Night Out: Archie, Barney, Harry
I Can Manage: Archie
Store Wars: Archie, Murray
Bunker Madness: Stephanie
No One Said It Was Easy: Billie, Gary
Small Claims Court: Barney, Archie
I'm Torn Here: Billie, Gary

[sm95fan]

Season 3:

Billie: Billie, Archie, Stephanie
The Business Manager: Archie, Roger Abbott
The Date: Billie, Roger Abbott
Norma Rae Bunker (Held over from Season 2): Mrs. Canby, Stephanie, Archie
Harry's Investment: Harry, Archie
Three's a Crowd: Barney, Archie, Katherine Logan
Happy Birthday, Stephanie: Stephanie, Archie, Barney
Growing Up Is Hard to Do: Part 1 & 2: Stephanie
Stephanie's Dance (Held over from Season 2): Stephanie, Archie
The Photo Contest (Held over from Season 2): Stephanie, Archie
Reggie-3, Archie-0: Archie, Reggie Jackson
Stephanie's Tryout (Held over from Season 2): Stephanie, Archie
The Night Visitor: Jose, Raoul
Blind Man's Bluff: Mr. VanR
A Blast from the Past: Billie, Archie
Sex and the Single Parent: Stephanie, Archie
Gloria Comes Home: Part 1 & 2: Gloria
Of Mice and Bunker: Archie
Relapse: Veronica
Love Is Hell: Stephanie, Billie
The Second Time Around: Archie, Katherine
West Side Astoria: Archie, Katherine
Billie Moves Out: Billie, Gary
Rabinowitz 's Brother: Gary
Death of a Lodger: Barney, Don Rickles
The Battle of Bunker III: Archie, Katherine, Stephanie
Gloria: The First Day: Gloria

[sm95fan]

Season 2:

Archie Alone: Part 1 & 2: Archie, Stephanie
Home Again: Archie, Stephanie
Hiring the Housekeeper: Archie, Mrs. Canby, Stephanie, Murray
The Wildcat Strike: Archie, Murray
Veronica and the Health Inspector: Veronica
Murray's Wife: Murray
The Camping Trip: Stephanie, Archie
The Incident: Mrs. Canby, Archie, Stephanie
Custody: Part 1 & 2: Stephanie, Archie
Barney the Gambler: Barney
Murray Klein's Place: Murray, Archie
Weekend Away: Murray, Archie
Stephanie's Science Project: Stephanie
Tough Love: Veronica
The Trashing of the Temple: Stephanie, Murray
La Cage Aux Bunker: Archie, Murray, Stephanie
Death of a Saint: Murray
Goodbye, Murray: Murray, Archie

[sm95fan]

Season 1 is harder to classify because the show had more of an ensemble feel, almost every episode included all the principals in some capacity:

Archie's New Partner: Archie, Murray
Edith Gets Hired: Edith, Archie
Archie and the Oldest Profession: Dottie, Archie, Murray
Edith Versus the Energy Crisis: Edith, Archie
Bosom Partners: Archie, Murray
Building the Restaurant: Entire cast
The Cook: Veronica, Fred, Archie, Murray
Murray and the Liquor Board: Murray, Archie
Thanksgiving Reunion: Original AITF cast
Barney and the Hooker: Dottie, Barney
Man of the Year: Archie
The Shabbat Dinner: Stephanie, Murray
Barney's Lawsuit: Barney
Blanche and Murray: Blanche, Murray, Barney
Murray's Daughter: Murray
The Ambush: Archie, Murray
The Return of Sammy: Archie, Sammy Davis Jr.
Archie Fixes Up Fred: Fred. Archie
Father and Daughter Night: Stephanie, Archie, Murray
Van Ranseleer's Operation: Mr. Van R, Archie
Veronica's Ex: Veronica
A Small Mafia Favor: Murray