United Kingdom, Aug. 20 -- Robin Williams brought "so much joy" to the set of Law and Order: Special Victims Unit.

The late comedian and actor surprised fans when he took a sinister turn as Merritt Rook - a man impersonating a police officer who asked people to perform criminal acts - in the long running procedural, and Mariska Hargitay has recalled the impact he had on set.

She told Variety: "The most memorable Law and Order cameo for me was Robin Williams. We had so much fun, and there was so much joy. He was such a light."

Williams starred in Authority, the show's 200th episode during its ninth season back in 2008.

Mariska, who has played detective Olivia Benson on the NBC crime drama since 1999, previously revealed she felt "so lu...