He's one of those actors where you can throw anything at him from an acting challenge point of view; you can shoot him, tie him up, torture him, dumb him down, make him all bloody and bruised, wring the emo from him and generally have him flung against a hard, inanimate object nearly every episode and he'll eat it up with a spoon and knock it out of the park every damn time.
As well as being known for modelling photos, he's also well-known for being in shows such as Supernatural (Dean Winchester), Dark Angel (twins Ben & Alec) and Smallville (Jason Teague), as well as being in some god-awful movies like Devour (Jake Gray) and the 3D remake of My Bloody Valentine (Tom Hanniger). His first big part was actually on Days of Our Lives, as Eric Roman Brady (Sami's twin).
Most recently outside of Supernatural he has done the Voice Acting for the titular villain of Batman: Under the Red Hood, the ISO character Gibson in the computer game Tron Evolution, a prequel to the movie Tron: Legacy, and Kyle Madigan, a character from the video game The 3rd Birthday, the 3rd game in the Parasite Eve series. In an example of What Could Have Been, he was in talks to play Leon Kennedy in Resident Evil Afterlife, before the delays and the extensive rewrites.
He also has possibly the most batshit crazy fanbase of all time. And with the hooker/child abuse fic, an obsessed fan telling everyone that she was his wife, a whole community devoted to how chubby he is, Live Journal's mind-boggling insistence that he's a douchebag with no sense of humor (yeah, right) who can't stand anyone, being assaulted at a convention, the Real Person Fic slash with Padalecki and the rumors of his inability to read (because he's pretty, you see, he can't have a brain) and so on and so forth, can you blame him for being a little terrified of them?
Despite it all, he is still considered to be the friendliest face on the set. He is often noted for taking the entire cast of Supernatural, even the extras, for drinks at the end of a shoot. Bang up guy.
He is married to longtime girlfriend Danneel Harris.