Malcolm-Jamal Warner, a star of '80s and '90s television best-known for playing Theo Huxtable on The Cosby Show, has died at the age of 54. The actor was in Costa Rica on a family vacation and drowned while swimming, Costa Rican National Police told ABC News.Authorities said that Warner's official cause of death was asphyxia, caused when the body is deprived of oxygen. He died near Playa Cocles, a beach in Limon, Costa Rica, according to police, adding that the actor was caught by a high current in the water and his body was found Sunday afternoon.