In Friday the 13th, the first name of Jason Voorhees is Jason.
Jason is the son of Pamela Voorhees, the killer in the original 1980 film Friday the 13th. The story reveals that Jason drowned as a child at Camp Crystal Lake while counselors failed to supervise him. Pamela blames the camp staff and begins killing the counselors who return to reopen the site.
A common mix-up is assuming Jason is the killer throughout the first movie. He is not shown as the adult murderer in that installment; his mother is responsible for the killings. Jason becomes the principal killer in later sequels, beginning with Friday the 13th Part 2 in 1981.
The character’s hockey mask is another detail often associated with the entire series, but Jason does not wear it in Part 2. He first appears in a hockey mask in Friday the 13th Part III, released in 1982. The mask then becomes his defining visual symbol.