Played by: John Ritter
- Attractive Bent-Gender: When dressed in drag in the Season 4 episode "Jack on the Lam." Chrissy's date found him especially hot.
- Camp Straight: Which certainly helps when pretending to be gay.
- Casanova Wannabe
- Catchphrase: "Oh lordy, lordy, lordy..."
- Chivalrous Pervert
- Cure Your Gays: Mr. Furley thinks his friendship with Jack did the trick when he moves in with a woman in the series finale.
- Faux Yay: Jack must pretend to be gay in front of the landlords so that he can live with two females.
- The Klutz
- Meaningful Name: Jack Tripper refers to the fact that Jack is a klutz.
- Mistaken for Gay
- Nice Guy
- The Pratfall:
- Punny Name: Just repeat his name slowly until you get the joke.
- Starving Student: The reason why he moves in with the girls.
- Supreme Chef: Jack attends cooking school for the first few seasons and later opens a French restaurant.
- Troll: Quite often when Mr. Roper makes a crack about him being gay (or sometimes just to get rid of him), Jack gets his own back by pretending to flirt with him.
- Unresolved Sexual Tension: Multiple episodes suggest that he and Janet might have a thing for each other, but nothing ever comes of it, and in the series finale, they both end up marrying different people.
Played by: Joyce DeWitt
- Brainy Brunette
- Cloudcuckoolander: Although she's Closer to Earth than Chrissy, she often overhears things and Hilarity Ensues.
- Jerkass Ball: In the episode where she gets a blonde wig and starts to act more and more rude to everyone because she enjoys all of the attention it gives her.
- Male Gaze: There tends to be countless of shots of her curvy behind, more often than Chrissy, even.
- Ms. Fanservice: Frequently seen in short skirts and nighties, although more conservative than Chrissy.
- She's Got Legs: Joyce DeWitt had a gorgeous set of gams and always wore pantyhose on the show, refusing to appear bare-legged even when her character was supposedly naked under a towel. She even appeared in several commercials for L'eggs.
- Tomboy and Girly Girl: Janet was initially somewhat of a tomboy to Chrissy's girly girl, although this became less pronounced after the first season.
- Unresolved Sexual Tension: With Jack.
Christmas Noelle "Chrissy" Snow
Played by: Suzanne Somers (Seasons 1-5)
- Absentee Actor: Chrissy was absent from numerous Season 5 episodes because of behind-the-scenes problems with Suzanne Somers.
- Brainless Beauty
- The Ditz
- Dumb Blonde
- Dumb Is Good
- Flanderization: In the first season, Chrissy was somewhat naïve but not really stupid; from Season 2 onwards, she Took a Level in Dumbass.
- Hair of Gold, Heart of Gold: She may not be too bright, but she compensates for that by being nice.
- Ms. Fanservice: The most of the show, frequently shown in bathing suits and short shorts.
- Preacher's Kid: Her father is a conservative Methodist minister, leading to the inevitable conflict over his daughter's decidedly non-traditional lifestyle. Amusingly, the actor who played Reverend Snow, Peter Mark Richman, is actually Jewish in real life.
- Put on a Bus: Following Suzanne Somers' departure.
- Punny Name: Which, she explains, is a result of her father being a big Bing Crosby fan.
Stanley and Helen Roper
Played by: Norman Fell and Audra Lindley (Seasons 1-3)
- And Starring: During their time on the show, Fell and Lindley got an "And Starring as the Ropers" credit.
- Aside Glance: Mr. Roper's specialty, after getting in a really good dig at his wife.
- Many times, this flirts with Breaking the Fourth Wall, as Mr. Roper looks straight at the camera (and thus the viewer) and smiles broadly.
- Awful Wedded Life: Albeit with occasional Aww, Look! They Really Do Love Each Other moments.
- Captain Obvious: Mr. Roper occasionally, prompting Mrs. Roper to reply, "Very good, Stanley."
- Cranky Landlord: Mr. Roper
- Iconic Outfit: Mr. Roper's cardigan sweaters, and Mrs. Roper's caftan dresses.
- Jerk with a Heart of Gold: Mr. Roper. He's very greedy, and often makes insulting comments about his wife and Jack. But deep down, he loves his wife, and cares about Jack, Janet and Chrissy.
- Put on a Bus: They move across town (and to their own spinoff show) at the end of season 3.
- The Bus Came Back: They make a one-shot return in the season 5 episode "Night of the Ropers".
- Secret Keeper: Mrs. Roper finds out Jack isn't really gay in the second episode, but goes along with the charade in her husband's presence for the rest of their time on the show.
- Sexless Marriage: The Ropers appear to have one of these for the most part, much to Mrs. Roper's chagrin.
- Single-Issue Landlord: Mr. Roper will not stand for a single man sharing an apartment with two women. Hence Jack's need for Faux Yay.
Played by: Richard Kline (Seasons 2-8)
- Ascended Extra: He made a one-shot appearance in the first season before being brought back as a Recurring Character in Season 2.
- Casanova Wannabe
- Hollywood Tone-Deaf: Larry's singing is terrible, as Jack and crew discover when he inadvertently hires Larry to sing at his restaurant.
- Jerk with a Heart of Gold
- Promotion to Opening Titles: In Season 4.
- Small Name, Big Ego
Played by: Don Knotts (Seasons 4-8)
- Always Camp: His loud Seventies clothes seem to make sense only in his mind.
- Ascended Extra: Furley was originally supposed to be a one-time character, but Knotts fit in so efficiently with the rest of the cast that he became a series regular.
- Casanova Wannabe
- Catchphrase: "Now hear this!"
- Dirty Old Man
- Expy: He's basically Barney Fife in a leisure suit.
- Landlord: Well, technically his brother Bart is, but Ralph is managing the building in his stead.
- Locked Out of the Loop: Like Mr. Roper, he is the only member of the cast who does not know that Jack is really straight.
- Unlike Mr. Roper, it's implied that Furley himself would not have a problem with the trio's living situation, especially given his own "swinger" lifestyle. It's just that his brother Bart, the building's true owner, would never stand for it.
Played by: Ann Wedgeworth (Season 4)
- All Women Are Lustful: Often considered to be TV's first "cougar".
- Chuck Cunningham Syndrome: Appeared in only 9 episodes and was last seen in "A Black Letter Day", given very little explanation on her disappearance, and was not mentioned after the episode.
- Mrs. Robinson: Part of the reason the character was quietly dropped was due to John Ritter's complaints about the implausibility of Jack spurning her attentions.
Played by: Jenilee Harrison (Seasons 5-6)
- Boobs of Steel: Cindy is noticeably the bustiest the four girls. It even gets joked about in the episode "Macho Man".
- Cute Clumsy Girl: Her primary attribute.
- Commuting on a Bus: In Season 6 she moves out of the apartment to attend UCLA, but continues to make regular appearances before eventually vanishing without explanation.
- The Cutie: A very sweet, bubbly, naive and approachable young girl.
- The Ditz: Albeit a milder example than Chrissy.
- She's Got Legs: While not as notable as Janet or Chrissy, Cindy showed off her fine set of legs in short shorts in the episode "Jack's Other Mother".
- Statuesque Stunner: 5'8" Jenilee Harrison actually stood taller than John Ritter in heels, and absolutely towered over petite Joyce DeWitt.
- Suspiciously Similar Substitute: Justified, as she's Chrissy's cousin.
Played by: Priscilla Barnes (Seasons 6-8)
- Deadpan Snarker: Often.
- Hospital Hottie: Terri is a Registered Nurse.
- Meet Cute: A non-romantic example. She first meets Jack as a hostile, uncooperative patient at the hospital where she works as a nurse.
- She's Got Legs: Much like Chrissy and Cindy before her.
- Suspiciously Similar Substitute: Averted. She may be an attractive blonde but she's neither ditzy nor klutzy like her predecessors.
- Who Wears Short Shorts?: Terri often wore these.