'Spotlight' and Leonardo Dicaprio also scored major wins in Oscars bellwhether.
The awards, seen as a bellwether of the all-important Academy Awards, were being closely watched as they were taking place amid a controversy over the lack of diversity in this year's list of Oscar nominees.
Spotlight took the prize for outstanding performance by a cast in a motion picture, the SAG equivalent of an Oscar.
PHOTO: REUTERSIt bested Beasts of No Nation, a drama about a child soldier, The Big Short, about the sub-prime mortgage crisis, Straight Outta Compton, a biopic about the N.W.A rap group, and Trumbo, about the life of acclaimed screenwriter Dalton Trumbo, who was the target of a witch hunt during the McCarthy era.
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In the acting honours, Leonardo DiCaprio won the best actor award for his portrayal of fur trapper Hugh Glass in the revenge thriller The Revenant.
Leo, 41, an Oscar favourite for the gritty survival story, beat competition from Bryan Cranston (Trumbo), Johnny Depp (Black Mass), Michael Fassbender (Steve Jobs) and Eddie Redmayne (The Danish Girl).
PHOTO: REUTERSIn the best female actor category, Brie Larson won for Room, in which she plays a kidnapped young woman living in captivity with her son.
But perhaps most notable at the star-studded ceremony were the number of black actors honoured as Hollywood reels from a fierce backlash over the lack of diversity in the Oscar nominations.
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Idris Elba scooped two awards, one for best supporting actor for Netflix's Beasts of No Nation, and one for best actor in a TV series for his role as a detective in the British crime drama Luther.
"Welcome to diverse TV," joked Idris, who was passed over for an Oscar nomination, as he presented an award during the ceremony at Los Angeles's Shrine Auditorium.
PHOTO: REUTERSUzo Aduba took home the award for outstanding actress in a comedy series for her role as Suzanne Crazy Eyes Warren in Netflix's prison comedy-drama Orange is the New Black. The TV series also won for the second consecutive year for best comedy ensemble.
"Look at this stage, this is what we talk about when we talk about diversity -- different race, colour, creed, sexual orientation," actor Laura Prepon, who plays Alex Vause in the series, told the audience, referring to the #OscarsSoWhite controversy.
PHOTO: REUTERSViola Davis meanwhile won best female actor for legal drama series How to Get Away With Murder, while Queen Latifah won for outstanding female actor in a television movie or miniseries for her role in HBO's Bessie, a biopic of the blues singer Bessie Smith.
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"We've become a society of trending topics," Viola told reporters backstage after her win, addressing the diversity controversy.
"Diversity is not a trending topic... Regardless of what's going on at the Academy, we will always find a way to be excellent."
PHOTO: REUTERSA number of actors, including Will Smith and his wife Jada Pinkett Smith, have said they will not attend the Oscars ceremony on February 28 over the diversity issue.
The Academy of Motion Picture Arts and Sciences, which picks the Oscar winners, has responded to the criticism by vowing to make major changes to promote diversity.
Here is the complete list of winners for the SAG Awards:
Outstanding performance by a cast in a motion picture: Spotlight
PHOTO: REUTERSOutstanding performance by a male actor in a leading role: Leonardo DiCaprio, The Revenant
PHOTO: REUTERSOutstanding performance by a female actor in a leading role: Brie Larson, Room
PHOTO: REUTERSOutstanding performance by a male actor in a supporting role: Idris Elba, Beasts Of No Nation
PHOTO: REUTERSOutstanding performance by a female actor in a supporting role: Alicia Vikander, The Danish Girl
PHOTO: REUTERSOutstanding performance by an ensemble in a drama series: Downton Abbey
PHOTO: REUTERSOutstanding performance by an ensemble in a comedy series: Orange Is The New Black
PHOTO: REUTERSOutstanding performance by a male actor in a drama series: Kevin Spacey, House of Cards
PHOTO: REUTERSOutstanding performance by a female actor in a drama series: Viola Davis, How To Get Away With Murder
PHOTO: REUTERSOutstanding performance by a male actor in a comedy series: Jeffrey Tambor, Transparent
PHOTO: REUTERSOutstanding performance by a female actor in a comedy series: Uzo Aduba, Orange Is The New Black
PHOTO: REUTERSOutstanding performance by a male actor in a television movie or miniseries: Idris Elba, Luther
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