The British SAS team from COD4 and MW2 was alright (mainly Captain Price):
The Black Ops 1 team was pretty cool too:
Every other Call of Duty game has had unmemorable protagonists IMO, even by COD standards. The worst offender is MW3... they shat on everything that made the characters from the first 2 MW games semi interesting, and I don't even remember any of the new characters. The villain was ass too, all of that build up for nothing.
It doesn't really matter though, I'll beat the campaign once and never play it again.
edit: how can I forget the greatest COD protagonist of all time, fucking Reznov.
Come to think of it, World at War had decent characters too. but I'm done talking about characters from fucking COD games, hahahah