Angel from Buffy the Vampire Slayer and Angel. Also, his human counterpart, Seeley Booth from the show Bones.
One is a brooding, personality-less vampire seeking redemption for the brutal murders he committed when he was evil.
The other is an equally brooding, personality-less human seeking redemption for the sniper kills he made when in the military.
Both characters are painfully dull, predictable, and constantly outshined by the other characters beside them, even very minor characters or temporary characters. They have nothing more to offer than being over-protective of the strong, independent women they are in relationships with (which comes off as degrading and disrespectful) and a "tragic," unoriginal backstory that leads to a half-assed redemption arc. They both lack vibrancy and flourish.
Now, I know David Boreanaz didn't create the characters, but he also didn't bring much intrigue or creativity to them, either.