I think Growing Pains is the best example of how a minor character that showed up near the end of the series became more popular than the main characters . Leonardo DiCaprio showed up in the last season of the show and played Luke, a runaway. The Seavers take him in as their foster child until his father comes back into his life and he goes back with him. Leo became the most well known award winning actor since appearing on Growing Pains and you rarely ever hear about the rest of the cast. They're still around but didn't find the same success after the series ended.

What other examples can you think of?

Erin Moran on "Daktari" near the end
Jerry Seinfeld on "Benson"
Ann Jilliann, better known as Ann Jillian, on "Hazel" near the end

George Clooney on THE FACTS OF LIFE

?Tom Hanks on Happy Days.

?Tom Hanks on Happy Days.

He had also been on Family Ties a couple of times playing Elyse's alcoholic brother.

He had also been on Family Ties a couple of times playing Elyse's alcoholic brother.

You're right. It's been so long since I've seen an episode of Family Ties I'd totally forgotten about that.

Ed.

Paul W. Walker in "Throb"; later he stopped using the middle initial
Michelle Pfeiffer in the short-lived sitcom "Delta House"

For actresses, a few come to mind:

Marisa Tomei, A Different World (1st season only. Regular, but Lisa Bonet was star then)

Elizabeth Banks, Scrubs (guest starred. Became more high profile in film and Hollywood after Hunger Games).

Michelle Rodriguez, Lost (Became more noticed after Fast and Furious. Tends to comes in action movies).

Hilary Swank, Beverly Hills 90210

Everyone has to start somewhere. Stars had to begin with small parts even if you didn't see them in it.

If you include variety shows like SNL, it's a long list of actors. Jennifer Lopez from In Living Color, Steve Carell from Daily Show.

Another sitcom actor:
Chris Pratt, Parks & Recreation
I think Chris Pratt's rise is more unexpected than John Krasinki from The Office, with Parks & Rec not as popular as The Office and Pratt's role of Andy somewhat less important than Jim on The Office. According to wikipedia, Chris Pratt wasn't a regular in the first season as well, but just recurring. Both stars became more fit as their careers advanced, with Chris Pratt losing a lot of weight.

Brad Pitt - Growing Pains
Melanie Griffith - Carter Country
Mark Hamill - Eight Is Enough (He played David in the pilot episode)

Jason Gordon-Levitt played DJ's weird friend on an episode of Roseanne. I think his guest appearance was what landed him on Third Rock from the Sun.

Bryan Cranston on Seinfeld as a dentist.

Milla Jovovich played a French foreign exchange student on Married with Children. I was so shocked when I came across that episode again a few years ago and realized it was her.

If I remember Matthew Perry was in an episode or two of Growing Pains playing Carol's boyfriend before becoming well known on Friends.

Bryan Cranston as an annoying next door neighbor of Doug and Carrie's named Ted Saksky on The King Of Queens before he was on Breaking Bad.

Jonathan Frakes was in one episode of The Dukes Of Hazzard years before he became well known as William Riker on Star Trek: The Next Generation.

Ed.

If I remember Matthew Perry was in an episode or two of Growing Pains playing Carol's boyfriend before becoming well known on Friends.

Bryan Cranston as an annoying next door neighbor of Doug and Carrie's named Ted Saksky on The King Of Queens before he was on Breaking Bad.

Jonathan Frakes was in one episode of The Dukes Of Hazzard years before he became well known as William Riker on Star Trek: The Next Generation.

Ed.You are correct about Matthew Perry. His final episode his character was killed off because of drunk driving. Bryan Cranston also appeared as Jerry's dentist on Seinfeld before Malcolm in the Middle started. Jonathan Frakes also guest starred on The Waltons as a flame of Erin's.

Goldie Hawn on the short-lived "Good Morning, World"
Molly Ringwald who was on "The Facts Of Life" was a pretty big star for a while in the 1980's
Janet Jackson who was on "Good Times" and "Diff'rent Strokes" has done pretty well as a singer

Mariska Hargitay (Law & Order: SVU) qualifies for this as prior to landing her Emmy-Winning role as Detective Olivia Benson on SVU she did extensive episodic guest work and had roles on a variety of short-lived, doomed, or just terrible shows. Among them are "Falcon Crest", "Can't Hurry Love" and "Doomstown."

Mariska Hargitay (Law & Order: SVU) qualifies for this as prior to landing her Emmy-Winning role as Detective Olivia Benson on SVU she did extensive episodic guest work and had roles on a variety of short-lived, doomed, or just terrible shows. Among them are "Falcon Crest", "Can't Hurry Love" and "Doomstown."

She was on E\R before that too. Which I'd hardly called "short lived" or "doomed". Although she didn't stay with the show for its whole run.

Ed.

Stanley Livingston was on an episode of Tarzan.

If we assume Matthew Perry from Growing Pains (minor role) to Friends as a "star" fitting in this category, then Courteney Cox on Family Ties (minor role) to Friends would also apply, Lisa Kudrow on Mad About You (minor role) as well as Matt LeBlanc, Married With Children (minor role) to Friends. With the exception of Jennifer Aniston, the rest of the Friends are more or less just TV stars, in my opinion. Definitely not as high profile as a film star or celebrity. But, still way bigger than ABC's Dancing With the Stars type of star.

Heath Ledger.

She was on E\R before that too. Which I'd hardly called "short lived" or "doomed". Although she didn't stay with the show for its whole run.

Ed.

She left E.R. to star in SVU; but aside from that short role on "E.R." her career had consisted of mostly episodic guest roles or recurring roles on shows that were ending or didn't last too long.

Valerie Bertinelli was on an episode of Apple’s Way a year before One Day At a Time

https://www.imdb.com/title/tt0513944/?ref_=nm_flmg_act_40

In the 80s Adam Sandler appeared on some episodes of The Cosby Show as one of Theo's high school buddies before becoming famous on Saturday Night Live and eventually becoming a huge movie star. Personally I can't stand him.

Brent Spiner guest starred in an episode of Night Court as basically a hick a few years before the premiere of Star Trek: The Next Generation in which he had his breakout role as android Data.

Ed.

Everyone has to start somewhere. Stars had to begin with small parts even if you didn't see them in it.

^^This. The thread could go on forever. Yawn.

Jay Leno was on the episode of Good Times where JJ thought he had VD.

Michael J. Fox was on an early episode of Night Court as a runaway at Christmas.

Joseph Mascolo (Stefano Dimera on DOOL) was on All In The Family.

^^This. The thread could go on forever. Yawn.

So don't read it then if you don't like it. Pretty simple.

Ed.

So don't read it then if you don't like it. Pretty simple.

Ed.

Fair enough.

Even the stars of Growing Pains themselves were pretty minor stars before making it big on the show.
Joanna Kerns did a lot of guest starring roles on several shows like the Walton's, The Love Boat, and Three's Company. She even did commercials. During Growing Pains and after the show ended she did a TON of Lifetime movies and now she's a successful director and still acts occasionally.
Tracey Gold was in lots of commercials as a child and even did some made for TV movies before and after Growing Pains. She still acts and is an advocate for anorexia since she struggled with it for years.
Kirk Cameron was in tons of commercials as a kid and did lots of TV movies, even he and his onscreen sister Tracey worked together before Growing Pains. He still acts even after becoming a Christian but in mostly Christian based movies and TV shows.
Alan Thicke was a talk show host in his native Canada before coming to the US. His US talk show bombed which allowed him to star on Growing Pains, he was in several things after that including Hope and Gloria. He even wrote the theme songs for Diff'rent Strokes and The Facts of Life.
Jeremy Miller is best known for his role as Ben on the show but he has had some minor roles since the show ended. He mostly works as a chef now but is still interested in acting.
Ashley Johnson is EVERYWHERE!!! She sings, does voice work, movies and guest star roles on TV.
Even though the stars of the show itself didn't become as famous as Leo DiCaprio or Brad Pitt, people still recognize them and know who they are. Growing Pains helped them in other ways and they made Growing Pains a very enjoyable and popular show that is still loved to this day. There are no small roles, just small actors. Some are meant to be super stars and some are meant to be not so super stars. :D

Before they became well known on Cheers both Shelley Long and George Wendt guest starred on an episode of M.A.S.H. But they were in separate episodes and not the same one.

Ed.