“The Help” also claimed the guild’s ensemble award, the show’s equivalent of a best-picture prize.
Davis and Spencer won as black maids going public with uneasy truths about their white employers in 1960s Mississippi.
Jean Dujardin won the lead-actor honor for “The Artist” as a silent-film superstar whose career crumbles when the sound era arrives. Christopher Plummer won for supporting actor as an elderly dad who comes out as gay in “Beginners.”
The wins boost the actors’ prospects for the same honors at the Feb. 26 Academy Awards.
Plummer would become the oldest actor ever to win an Oscar at age 82, two years older than Jessica Tandy when she won best actress for “Driving Miss Daisy.”
Backstage, Plummer joked about whether he would like to win an Oscar, an honor so elusive during his esteemed 60-year career that he did not even receive his first Academy Award nomination until two years ago, for “The Last Station.”
“No, I think it’s frightfully boring,” Plummer said. “That’s an awful question. Listen, we don’t go into this business preoccupied by awards. If we did, we wouldn’t last five minutes.”
Spencer, a veteran actress who had toiled in small TV and movie parts previously, had a breakout role in “The Help” as a brassy maid whose mouth continually gets her in trouble.
“I’m going to dedicate this to the downtrodden, the under-served, the underprivileged, overtaxed — whether emotionally, physically or financially,” Spencer said.
On the television side, comedy series awards went to “Modern Family” for best ensemble; Alec Baldwin as best actor for “30 Rock”; and Betty White as best actress for “Hot in Cleveland.”
“You can’t name me, without naming those other wonderful women on ‘Hot in Cleveland,’” the 90-year-old White said. “This nomination belongs to four of us. Please, please know that I’m dealing them right in with this. I’m not going to let them keep this, but I’ll let them see it.”
The TV drama show winners were: Jessica Lange as best actress for “American Horror Story”; and Steve Buscemi as best actor for “Boardwalk Empire,” which also won the ensemble prize.
For TV movie or miniseries, Kate Winslet won as best actress for “Mildred Pierce,” while Paul Giamatti was named best actor for “Too Big to Fail.”
Before the official ceremony, the Screen Actors Guild presented its honor for best film stunt ensemble to “Harry Potter and the Deathly Hallows: Part 2.” The TV stunt award went to “Game of Thrones.”