Robin Williams is to go back to his TV roots with a guest appearance on hit U.S. detective show Law & Order: Special Victims Unit.

The Good Morning Vietnam star is set to ditch his funnyman persona and take on a more serious role in the show.

After his breakthrough role in 1980s sitcom Mork & Mindy, Williams’ career has mainly focused on feature films but the appearance on Law & Order will mark his return to the small screen.

The episode is due to start filming later this month (Mar08) and will air in the U.S. on 29 April (08).