British thesp Stephen Fry is joining the cast of “Sherlock Holmes 2” for Warner Bros. opposite Robert Downey Jr. as Mycroft Holmes, older brother of the titular character.

The Holmes sibling appears in four Sherlock Holmes stories as a character who’s smarter than his younger brother — but far lazier. Fry announced Saturday that he had taken the role during a radio program on BBC.

Fry’s perhaps best known in the United States for the six-part 2008 television series “Stephen Fry in America.” He also has a recurring guest role on Fox series “Bones.”

Warner recently tapped Swedish thesp Noomi Rapace as the female lead in “Sherlock Holmes 2” in her first English-speaking role. Studio’s set a Dec. 16, 2011, release date with Guy Ritchie returning as director along with the rest of the cast and producers, including Dan Lin, Joel Silver, Susan Downey and Lionel Wigram.

Warner tapped Kieran and Michele Mulroney to pen the sequel last fall.