Henry on The Amazing Chan And The Chan Clan, in a way. He's dressed very conservatively (except in the comic version of episode 3), but his pants are rather tight and he's drawn as being the "hunk" of the boys. Plus there's his voice.
Avatar: The Last Airbender has Prince Zuko. Though he may not have been intended as such at first, the creators quickly caught on and lampshaded the hell out of his Mr. Fanservice status in the second and third seasons.
The Legend of Korra has Mako, who, unlike Zuko, seems completely intended as one from the beginning, as he's actually had more outfit changes than Korra and his scenes normally include a lot of unnecessary panning and posturing. Even the creators, his bio on the Nick website and his voice actor make it a point to mention that Mako is good-looking.
Braeburn from My Little Pony Friendship Is Magic seems to be an unintentional example of this, although you wouldn't know it from the prominence of his Estrogen Brigade within the pony fandom. Between him and Big Macintosh, the Apple family seems to be one of Equestria's few sources of good looking (by pony standards) eligible bachelors with speaking roles.
The other source would be the royal family, although Prince Blueblood's personality has made him a lot less popular than his aunts. He is in many ways a Bait and Switch subversion of this trope.
And now we have Flim and Flam. Gorgeous singing voices, lovely speaking voices, charming personalities until they start acting like douchebags to the apples, that is, pretty boy (Flim and, to an extent, Flam), gorgeous manes (even if they look like bacon), a tendency to be rather well dressed, bright and shining eyes … they honestly have a rather large fanbase, not as big as any other example for the show; but there are still plenty of fans fawning over them. And though not everyone agrees, they're a hint adorkable as well. Must be the bowties or something.
Jack himself in Samurai Jack mix badass with a gentle soft spoken nature toward his allies, a protective—almost parental—personality toward the weak, add a good dollop of Japanese Politeness and sprinkle with copious amounts of Shirtless Scenes, and this is what you get.
Chat up the female Galaxy Rangers fanbase; all three of the male leads have fangirl-attracting qualities. Take your pick:
The green-eyed, blond Troubled, but Cute young man with a dark past, but a compassionate streak regardless?
Red Arrow, a reoccuring character on Young Justice, was transformed from Green Arrow's hat-with-feather-wearing sidekick in the first episode to a sexy solitary superhero with a uniform that shows off his fantastic arms and even wearing an even more fantastic suit for the majority of episode 10.
Superboy is a much straighter example. Show events go out of their way to make sure he loses his shirt somehow,and he plays up many different fanservice tropes.
