does he hide his face?
Yes he wears a hockey goalie mask in "Friday the 13th Part III".
Introduction
The trademark hockey goalie mask did not appear until "Friday the 13th Part III".
who played jason voorhees in friday the 13th Ari Lehman who is this character? He is the main character from the "Friday the 13th" movie series.
Yes, with a hockey goalie mask. Yes and there is an unmasking shot at the end. Yes, he uses a hockey goalie mask.
Jason Voorhees Jason Voorhees Jason Voorhees
Introduction Men behind the mask Introduction
Tom Savini's initial design has been the basis for many of the later incarnations. The trademark hockey goalie mask did not appear until "Friday the 13th Part III". Since "", filmmakers have given Jason superhum  so the stunt coordinator Cliff Cudney brought in Steve Daskawisz. Daskawisz filmed all of the scenes except the opening sequence and the unmasking shot at the end; Gillette returned for the unmasking scenes.  The trademark hockey goalie mask did not appear until "Friday the 13th Part III". 
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Jason Voorhees [SEP] Introduction
Since Lehman's portrayal, the character has been represented by numerous actors and stuntmen, sometimes by more than one at a time; this has caused some controversy as to who should receive credit for the portrayal. Kane Hodder is the best known of the stuntmen to portray Jason Voorhees, having played the character in four consecutive films. The character's physical appearance has gone through many transformations, with various special makeup effects artists, including Stan Winston, making their mark on the character's design. Tom Savini's initial design has been the basis for many of the later incarnations. The trademark hockey goalie mask did not appear until "Friday the 13th Part III".