Malcolm-Jamal Warner, the actor, who has died aged 54, was cast as Theo Huxtable in the sitcom The Cosby Show at the age of 13, and over the course of some 200 episodes became one of US television’s best-known teenagers.

Over the course of the show’s eight year run, this moment was not always taken as a given; the son, Theo Huxtable, was for years presented as a chronic underachiever, more interested in the typical trappings of teenage boyhood—friends,

Mr. Warner, who played the only son of Bill Cosby’s character on the beloved 1980s sitcom, drowned in Costa Rica.