Jason Voorhees is the homicidal maniac from the Friday The 13th films. He is thought to have killed at least 146 people.
I was listening to an old edition of Deadpit radio the other day and the subject of Voorhees' baldness came up. They briefly discussed a theory that as a hermit living rough in the woods, Jason lost his hair through lack of nutrition. I decided to explore his baldness in more detail.
In the original Friday The 13th film, Jason is a child and completely bald. Makeup artist Tom Savini wanted him to resemble a "hydrocephalic, mongoloid pinhead", with a dome-shaped head.
When he returned as a young adult in Part 2, Voorhees had somehow managed to grow some long, straggly ginger hair.
Part 3 is when Jason's iconic hockey mask makes it's first appearance. Behind the mask, Jason is once again bald, and remains that way for the next 6 films.
His hair makes a brief comeback in Jason Goes To Hell - The Final Friday, but by now he is practically a zombie and it has withered away to a few pathetic strands.
For the 2009 remake, Jason's look was based on parts 2 and 4. From what I can tell, he does appear to have a little hair but again it is very sparse (I haven't seen the remake yet).
I think the guys from Deadpit are right and Voorhees most likely has alopecia totalis or universalis rather than androgenic alopecia (male pattern baldness). These forms of baldness are not classified on the Norwood scale which means unfortunately Jason does not have a Norwood Rating.
Norwood Rating : n/a