Trust me, you weren’t the only one. 
Bill Murray in “Zombieland.”
John Candy in “JFK.”
And Charlie Sheen who was fantastic in “Being John Malkovich.”
This list will be huge; it might be easier to name A-listers who haven’t done this at some point. Also, I don’t think leading a movie or two makes one an A-lister, though I could be wrong on my definition of A-lister versus standard convention. Guy Pearce, in my mind, is not an A-lister. A-listers sell movies. The drolling masses are not going to a movie because Pearce is the star, whereas Cruise and Diaz sell Knight and Day. I would even have issues calling Statham, whose name sells a certain type of inexpensively made movie (which I usually enjoy) as an A-lister. Maybe an A-minus or B-plus.
Still, I have no clue, nor do I really care about, the Hollywood pecking order and accept that my view may be narrower than the accepted norm.
Matt Damon appeared in a very small bit part in the movie Finding Forrester, with Sean Connery. Anna Paquin was also a third-bill as Jamal’s girlfriend.
StG
My favorite quote from Caine concerning Jaws: The Revenge.
“I have never seen the film, but by all accounts it was terrible.
However I have seen the house that it built, and it is terrific.”
I think the king would be Harvey Keitel. I think he really loves to be in “art” films, and loves to be in films that are innovative or edgy. I suspect he either partially funds these films or takes a reduced wage. However, in regards to this thread, it’s tough to argue that he’s an A-lister.
Overall though, I think there’s tons of great actors who could get more money, but love the art, so they often take non-starring roles. I’ve read on more than one occasion, for example, that some actors just wanted to work with Spielburg or Scorsese once in their careers, and were willing to take a much smaller role or bit part.
Sir John Gielgud in I’m Gonna Get you Sucka - though that might count as a cameo, and not a B role?
Christian Slater had 1 line in the Star Trek 6 movie.
You mean John Vernon?
He also had a small bit part in Chasing Amy.
How about Drew Barrymore in Donnie Darko? It was too big a role to be a “bit part” or “cameo,” but she was certainly not the star of the film.
While the main stars were by no means unknowns, seeing Charlie Sheen killed off in the first few minutes of Mission: Impossible was certainly odd. I think there might have been some sort of story about how that came to be, as it wasn’t really a celebrity cameo or anything.
Does this count?
Sean Connery played King Richard in Costner’s Robin Hood. I believe he had about a 20 second camera shot.
…or am I just lost?
You glossed over both Magnolia and Tropic Thunder, both of which he was in and neither of which was a Tom Cruise movie.
Is there a single actor who doesn’t meet the criteria of the OP? Tom Cruise absolutely does. Though in fairness, perusing his imdb listing shows a mere four films that aren’t “Tom Cruise movies.” (Magnolia, Tropic Thunder, The Outsiders, and Austin Powers in Goldmember.)
I think the much more interesting question is which actors have the highest percentage of personal star vehicles on their resume? Tom Cruise may be at the top of the list. Kevin Costner is up there, but Tom has him beat.
Not Charlie Sheen, but Emilio Estevez.
B roles before reaching A status is quite a different thing from B roles after or more importantly, during the peak of A status.
Also, an A-list cameo is quite a different thing than a B role.
Also, have a major role in an indy movie or low rent comedy is not quite the same as getting to A list…
And cost himself a whole lot of money by taking a straight paycheck instead of getting a percentage of the film.
One of my favorites is Jimmy Cagney won an Oscar for playing George M Cohan in “Yankee Doodle Dandy”. One scene has Cohan exchanging good-natured ribbing with his rival Eddie Foy, played by Eddie Foy Jr. Several years later Bob Hope starred as Foy Sr in a biopic. Cagney reprized the role of Cohan in another ribbing scene that featured both Hope and Cagney dancing on a table.
Bette Davis as Empress Catherine the Great in the Robert Stack film about John Paul Jones.
It seems like Nick Cage is overextending his A-List status. Saturation. Can’t go a season without seeing Cage in some moneymaking role. He seems to have degraded to a B+.
Saving Private Ryan had a bunch, but many war movies tend to be ensembles anyway. Vin Diesel (for that short window where he was an A-lister), Matt Damon (although he was the title character, he was only on screen for the final act) and Tom Sizemore.
It is hard to argue that Ben Affleck was an A-lister immediately after Good Will Hunting, but he had a B role in Shakespeare in Love.
Judi Dench seems to have made a career out of being the A-list of the B-roles. Just about all of her work is as supporting cast, but she has a better than 50% chance of being nominated for an Oscar in that role.
Women tend to have this role more often than men, as “the hero’s girlfriend” is pretty much always a B role.
Same year Bruce Willis prevented Armageddon right in front of him – sure as Giovanni Ribisi was the one toiling away in the Boiler Room, and something something Dogma.
And, of course, have the opportunity of impressing said director in person in the hopes of a major part in their next movie?
And completely stole the scene. Indeed, in that movie, it seems that Costner is very much the supporting actor to everyone else.
And she completely stole Shakespeare in Love.