<P> Star Trek: The Next Generation is an American science fiction television series which aired in syndication from September 1987 through May 1994 . It is the second live action series of the Star Trek franchise, and comprises a total of 178 episodes over seven seasons . The series picks up about 75 years after the original series is said to have taken place . </P> <P> The main cast consisted of Patrick Stewart as captain Jean - Luc Picard, Jonathan Frakes as his second - in - command William Riker, Brent Spiner as chief of operations Data, LeVar Burton as chief engineer Geordi LaForge, Marina Sirtis as counselor Deanna Troi, Michael Dorn as chief of security Worf, and Gates McFadden as Dr. Beverly Crusher . McFadden left the show after the first season and was replaced for the second season with Diana Muldaur as Dr. Katherine Pulaski, but returned for the third season and remained with the cast thereafter . Wil Wheaton starred as Wesley Crusher in seasons 1--4, returning for guest appearances in seasons 5 and 7 . Denise Crosby played chief security officer Tasha Yar in the first season but her character was killed in the episode "Skin of Evil". </P>

Star trek the next generation number of episodes