Yes, you can write to cast members. If you would like to write to cast members of Star Trek: The Next Generation, Star Trek: Deep Space Nine, Star Trek: Voyager or Star Trek: Enterprise, please address your letter to:

Actor's full name
c/o the corresponding Star Trek series
Paramount Pictures
5555 Melrose Avenue
Hollywood, California, 90038-3197

To contact cast members from the original Star Trek series, address your letter to:

Actor's full name
c/o Lincoln Enterprises
P.O. Box 691370
Los Angeles, California, 90069

Please note that if you would like an item, such as a photograph, autographed by a cast member, be sure to enclose it along with a self-addressed stamped envelope. Please remember that the actors are sent a large amount of mail from the fans and, although they do their best to respond, their busy schedules mean they may be unable to reply to every single piece of mail.