Beginning April 3, Jeff Goldblum joins the cast of Theresa Rebeck’s Broadway comedy Seminar. He succeeds “Harry Potter” actor Alan Rickman in the role of Leonard. Goldblum, star of stage and screen, made his Broadway debut in Two Gentlemen of Verona in 1971 and is known for his work in films such as “Jurrasic Park.” Seminar welcomes not only him into the production this month, but also Justin Long and Zoe Lister-Jones. They are expected to perform through May 27.