That was over 32 years ago in 1989.
Today he is 51, and has starred in 89 movies in total, 82 since Heathers was released.
In Heathers, I think Christian Slater looks:
Heathers scores 7.3 out of 10 on The Movie Database.
Christian Slater's first acting role was as 'uncredited' in Sherlock Holmes: The Strange Case of Alice Faulkner, released in 1981 when he was 12.