Actor Robin Williams arrives at the premiere of 'August Rush' at The Ziegfeld Theater, in this Nov. 11, 2007, file photo in New York. [Agencies]

Robin Williams will guest star on "Law & Order: Special Victims Unit," but don't expect him to bring laughs to the NBC crime drama.

Williams is playing an "engineer whose life has gone terribly wrong" and who faces serious repercussions, series spokeswoman Pam Golum said Tuesday. The episode, which films later this month, is scheduled to air April 29.

After his breakthrough role on the 1980s sitcom "Mork & Mindy," Williams' career has mostly centered on a mix of movies, including "Good Morning, Vietnam," "Dead Poets Society" and "Patch Adams." He won an Academy Award for 1997's "Good Will Hunting."

The "Special Victims Unit" episode with Williams, titled "Authority," is the show's 200th, Golum said.