Yes, MARTIN is a Scrabble word!

Letter values in Scrabble US: M 3, A 1, R 1, T 1, I 1, N 1.

Is it a valid word?

MARTIN is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

French bishop who is a patron saint of France (died in 397)
United States actor and comedian (born in 1945)
United States actress (1913-1990)
United States singer (1917-1995)
any of various swallows with squarish or slightly forked tail and long pointed wings; migrate around Martinmas

Also: st. martin, steve martin, mary martin, dean martin, dino paul crocetti.