Bret Harrison has amused me thoroughly ever since I first saw him as Brad on Grounded for Life. While I didn't get to see him on The Loop, my fond GfL memories are what led me to check him out on Reaper (well, that and Kevin Smith's involvement). Factor in his occasional guest appearances elsewhere, and he's been around a bit for a guy his age.
He's really got an everyman, boy-next-door quality about him (which is probably why he was so great on GfL...he played the boy next door). But he also manages to shine in starring roles. Plus, he's been in a movie with Burt Reynolds, which I believe legally doubles his overall coolness.
I think that, in time, he may eventually become my generation's Robert Urich (minus the untimely death of natural causes)...funny, likeable, a few hit shows, a lot of misses, but always more respected and popular than the show he was on.