Which actor(s) didn't go on to a greater success than you thought they would have?
Two that come to mind are Ralph Carter from Good Times and Topher Grace from That 70s Show.

I remember Topher saying he didn't think he was leading man material. Maybe his agent didn't get him those roles because of that.

After seeing Richard Grieco on “21 Jump Street,” I thought that I was seeing the next James Dean or even the next Marlon Brando, emoting on tv with the heady likes of Johnny Depp and Dustin Nguyen. Alas, the introspective Mr. Grieco just never seemed to grow and mature as a serious thespian. I think he’s currently starring in those God-awful science fiction tv films on the Sy-Fy Channel.

Similarly, I thought that Lorenzo Lamas was going to be the next Robert DeNiro or even the next Glenn Scarpelli after seeing him perform as the iconoclastic and uber-cool Reno Raines
on “Renegade.” Yet, Mr. Lamas has floundered in his acting career in much the same way that the acting careers of Scott Baio, Willie Aames and Brett Butler have nose-dived.

Honorable mention: Josh Meyers, Scott Caan, Alec Baldwin and Roz Kelly.

I thought that John Henton, who played Overton on Living Single, was going to end up headlining a big sitcom. He eventually was in a bad car accident that set his career way back,

I think that Jane Levy has the talent to be an Hollywood all-star, and she's currently the best television actress nowadays.
She was not yet given a real chance in movies, and even in television she didn't landed in shows that could grant her an iconic role that would launch her.

Lecy Goranson "wasted" her best years not acting. She was really good as a kid in Roseanne, and also in The Conners, after the first season in which she was maybe a little rusty, she's doing great.
I always wondered what she could acheive if she opted to stay in Roseanne instead of giving up the role to attend college.

Jennifer Esposito didn't realized her full potential. She's having a pretty good career and starred in different successfull shows, but never as the main. She has the talent to carry a show in which the audience can fully recognize her.
Also, I would love to see her again in a sitcom, she has the timing and the mimic, unfortunately she hasn't been in one since Spin City.

Then, two bigger stars:
Sarah Michelle Gellar could've been a far greater star, but she chosed family over the industry (and I'm glad for her).
Michael J. Fox for obvious reasons.

James Stacy
Pete Duel
Peter Brown
Darlene Gillespie

Jennifer Esposito didn't realized her full potential. She's having a pretty good career and starred in different successfull shows, but never as the main. She has the talent to carry a show in which the audience can fully recognize her.
Also, I would love to see her again in a sitcom, she has the timing and the mimic, unfortunately she hasn't been in one since Spin City.
Jennifer Esposito is not lead actress material. She added nothing to NCIS, and her replacement Marisa Ramirez was an improvement on Blue Bloods.

I think that Jane Levy has the talent to be an Hollywood all-star, and she's currently the best television actress nowadays.
She was not yet given a real chance in movies, and even in television she didn't landed in shows that could grant her an iconic role that would launch her.

Lecy Goranson "wasted" her best years not acting. She was really good as a kid in Roseanne, and also in The Conners, after the first season in which she was maybe a little rusty, she's doing great.
I always wondered what she could acheive if she opted to stay in Roseanne instead of giving up the role to attend college.

Jennifer Esposito didn't realized her full potential. She's having a pretty good career and starred in different successfull shows, but never as the main. She has the talent to carry a show in which the audience can fully recognize her.
Also, I would love to see her again in a sitcom, she has the timing and the mimic, unfortunately she hasn't been in one since Spin City.

Then, two bigger stars:
Sarah Michelle Gellar could've been a far greater star, but she chosed family over the industry (and I'm glad for her).
Michael J. Fox for obvious reasons.

Michael J Fox was an A Lister and was in those Back to the Future movies and several other films and he was on a TV show called "Spin City" which was on for numerous seasons. He would probably still be acting it if it wasnt for his Parkinsons.

Some child and teenage actors quit the business (they made their money and tired of it) and went to college, got degrees and had a professional life. Tracey Gold (or was it Missy?) became a psychologist. I think Ralph Carter ended up going to college and getting a good job. Not all kid actors turned out like Dana Plato and Gary Coleman.