Undoubtedly part of the reason for the success of Sylvester Stallone and Arnold Schwarzenegger in their hey day - just like Steve Reeves, Reg Park and the other body builders turned stars of Hercules and other Italian sword and sandal flicks who inspired them. And continues with their successors Vin Diesel and Dwayne "The Rock" Johnson.
The late Burt Lancaster, a former circus acrobat before he took up acting, was one of Hollywood's earliest examples.
Paul Bettany as Geoffrey Chaucer in A Knight's Tale. Spends his entire very memorable introduction sequence (several minutes long) completely naked and in desperate need of a scrubbing. He's naked again not long after that.
Steve also sporadically evokes this in the sequel - that tight t-shirt (and later on, the white tank top) really shows off those muscles...
Casino Royale is just chock full of naked, shirtless and tiny-swimsuit-wearing Daniel Craig. The scene to the right was pure dumb luck due to where they were shooting (the water was too shallow so Craig couldn't swim and had to stand up). The director decided to Throw It In and Craig proved he could live up to Bond's Memetic Sex God status.
Salvadore from Couples Retreat is never seen with a shirt on.
In Date Night, Holbrooke Grant (Mark Wahlberg) spends the whole movie with his shirt off, and just put them on near the end when he's asked for it.
Thor from the 2010 movie Kaboom is nothing but a Mr. Fanservice.
Trent, the male protagonist of Lawn Dogs, has several shirtless scenes, wears shirts with varying numbers of buttons undone, and has a full nude scene near the beginning of the film for good measure. Not to mention all the sweat he works up.
Magic Mike is a movie about male strippers. The Powers that Be were aware of this, as one of the bonus features of the DVD was all of the stripping scenes strung together without any of that pesky dialogue or plot getting in the way.
In The Mummy and The Mummy Returns, Oded Fehr's character Ardeth Bey acts as fan service with fighting scenes and an accent. To some extent most of the male cast including Imhotep...once he is less corpse and all man.
The Outsiders is FULL of this. It has a bunch of guys who are usually wearing tight shirts or even no shirts. There's even a scene where Rob Lowe comes out of the shower wearing only a towel. Later, he's laying on the couch with his knees up so it looks like he's naked.
Jean-Claude Van Damme, full stop. He must have a contract stipulation that states he must show his bare ass at least once in every movie he's in, and he spends a good amount of combined time shirtless.
Teddy from Neighbors, natch, when you're played by Zac Efron, you're automatically this. It also helps him get a post-college career at Abercrombie & Fitch, and there's a prolonged Shirtless Scene at the end that seems to say "Thanks for watching, ladies, and now: here's the reason you bought a ticket."
Garrett Dillahunt (Hogan) in The Scribbler, In-Universe. Not only does he have many shirtless scenes, but as the only guy in an otherwise all-female psychiatric halfway house, he's more than happy to sexually service his fellow inmates.