Arm. Leg.
arm or leg
Try gut.
tar
dog? as in sea dog Possibly tar
The only word I know of is hasheesh, another name for canabis
They all have 3 letters, but "red" and "tan" have exactly 3 letters.
The actor and presenter you are referring to is "Matthew Fox." He has a first name with 7 letters and a surname with 3 letters.
The Huge star name with 3 and 5 letters is the Red Giant.
Lev Tolstoy (was a Russian novelist)
apt
Ape
cot