Patrick Troughton portrayed the 1st regeneration of the Doctor. He starred in 21 Doctor Who episodes. As SerpentSmaher said, Troughton resembled Mo Howard. I think that Troughton's Doctor was modeled after MR. Howard. Mo Howard was great in the Three Stooges but not in Doctor Who.
This was not a very good incarnaton of the Doctor. I give Troughton a 2 star rating.

Mo Howard of the Doctor Who's.  He get's irritating, but he had some good episodes.  NOT the Colin Baker "Two Doctors" episode though.