SAN FRANCISCO — Shirley Manson turned Garbage into gold. She accomplished this bit of pop culture alchemy during her days as the lead singer of the alternative rock band Garbage. In the mid-1990s, the Scottish siren drew big crowds with her distinct voice and looks.

Now, Manson is acting. She’s currently playing Catherine Weaver in the Fox Network series “Terminator: The Sarah Connor Chronicles,” airing at 8 p.m. Fridays.

Weaver is the chief executive officer of a massive company at the center of the whole Terminator mythology. Even Weaver is one of the shape-shifting killers from the not-to-distant future.

“I’m 42. I have been in bands since I was 15. There gets to a point where you are stepping out in front of 100,000 people and your blood pressure doesn’t change. I felt like I wanted to do something in my life that scared me. You get to a point in your life where everything is too comfortable,” Manson said during an interview at WonderCon, the comic-TV-movie convention.

Manson has arrived for an interview a few minutes before she will step in front of an auditorium of fans. The black coat she is wearing makes her porcelain skin seem even more achromatic. Her Raggedy Ann-red hair is tightly pulled back, emphasizing her piercing eyes.

Manson found success with Garbage. The group’s first self-titled album sold more than 4 million copies and produced chart-topping singles “Only Happy When It Rains” and “Stupid Girl.”

But the glitter of music eventually faded. In 2003, Garbage disbanded. The band got back together in 2005 for a fourth album. But it was about that time that the business lost all its appeal to Manson.

The decision to walk away from the music world was sparked by industry changes.

“I was sickened by my record company’s approach, which was, to me, essentially an uncreative process. I felt like there was nothing I was ever going to be able to do that was going to please them. I didn’t want to play the corporate music gig where they want women to make nursery rhymes. I wasn’t prepared to do that,” Manson said. “The business is not being run in a smart fashion.”

She knows the music business well. Manson was inspired by her mother, a big-band singer. After providing backup vocals and playing keyboards for Goodbye Mr. Mackenzie, Manson worked as a solo artist under the name Angelfish. She hooked up with Garbage in 1994.

Her leap into acting was a baptism of fire. She not only took on the demands of appearing in a weekly network drama, but landed a role in a show loaded with special effects.

“I feel like I have learned so much over the course of the series and started to understand more about the process of acting and making a TV show. I have just started to learn how to develop a character,” Manson said.

Being in front of big crowds is normal for Manson. Acting overwhelmed her.

“It is the most extreme thing I have ever done in my life. You have to literally learn how to do something in front of millions of people. I think if I had known how big the role was going to be, I would have collapsed,” Manson said.

Manson credits her fellow “Terminator” actors, especially Richard T. Jones, with helping her become more familiar with acting. The help was needed because she’s found acting and music to be completely different disciplines.