a guy (doesn't have to be young) who cares about his appearance, looks, and image. he might wear expensive clothes, jewlery, or style his hair. basically he wants to look good as much as possible.
IS NOT A METROSEXUAL. two different things. a metrosexual is related to embracing the gay culture. a pretty boy would punch you in the face if you said anything like that to him and might even hate gay men.
pretty boys: jonny depp, vin diesel, timberlake, will smith