George Clooney, Julianna Margulies Among Screen Actors Guild Nominees
Clooney, DiCaprio and Pitt, three of Hollywood's biggest stars, will square off against two relative unknowns, Demian Bichir and Jean Dujardin, in the category of best actor.
Williams is joined by Glenn Close, Viola Davis, Meryl Streep and Tilda Swinton in the race for best actress.
The five movies nominated for best cast ensemble are The Artist, Bridesmaids, The Descendants, The Help and Woody Allen's Midnight in Paris.
Fresh from her Emmy win, Melissa McCarthy was also nominated for her supporting role in the movie comedy Bridesmaids.
TV nominees include the comedic casts of the heavily nominated Modern Family, as well as 30 Rock, The Big Bang Theory, Glee and The Office. Dramatic casts nominated are Boardwalk Empire, Breaking Bad, Dexter, Game of Thrones and The Good Wife.
Individual TV actors nominated include Julianna Margulies, Steve Buscemi, Kathy Bates, Bryan Cranston, Jessica Lange and Glenn Close.
For a full list of nominees, go here.
As previously announced, Dick Van Dyke will present the Life Achievement Award to his TV costar of 50 years ago, Mary Tyler Moore.
The 18th Annual Screen Actors Guild Awards will be broadcast live from the Los Angeles Shrine Exposition Center on Jan. 29.