Lowe

Despite Arthur Lowe's exhaustive theatrical, film and TV career spanning five decades, it's rather inevitable that, in the final reckoning, he's probably remembered by many for one role and one role only.
Lowe's alter ego, the pompous* Captain Mainwaring - the part he played for almost 10 years - must ultimately have weighed him down. 
He will have had as many, if not more, Dad's Army fans come up to him in the street and shout 'Stupid Boy' than Alan Partridge acolytes have yelled 'AHA!' at Steve Coogan whenever he's nipped out for a pint of milk.

*Who remembers him voicing over the Mr. Men animated series back in the late seventies? Towards the end of Lowe's career he was a functioning alcoholic and could, allegedly, be every bit as pompous as Mainwaring himself. I'm not sure if Roger Hargreaves ever wrote a Mr. Pompous book, but here's Mainwaring Lowe reading Mr. Uppity. Fall in at the back.