Sherry Lansing (search), a powerful studio boss who carved the career path for female Hollywood executives, said Tuesday she will leave her post as chairwoman of Paramount Pictures (search) at the end of next year when her contract expires.

At Paramount, Lansing was a key player in the Oscar-winning blockbusters "Titanic," "Braveheart" and "Saving Private Ryan." But the studio has seen a string of flops and box office disappointments in recent years, including "The Stepford Wives."

"This was 100 percent my choice," the 60-year-old Lansing said in an interview. "I've been doing this job for 12 years and I've loved every moment of it. I wanted a new challenge. I want to do something completely different, something to give back to the community."

Lansing serves on the boards of several nonprofit groups and is a supporter of Democratic presidential candidate John Kerry (search). Lansing had planned to spend Tuesday evening watching election results with Kerry, but spent the day in Los Angeles "calming nervous executives" after her decision was made public prematurely.

Her announcement follows several management shake-ups at parent company Viacom Inc., including the departure of Jonathan Dolgen, who had shared power with Lansing at Paramount.

It also comes after several years of lackluster performance at Paramount and pledges by Viacom's management, including Viacom chairman Sumner Redstone, to revitalize the studio.

Lansing became the first female president of production for a Hollywood studio in 1980 when she was named to that job at 20th Century Fox Productions.

She later became a partner with producer Stanley Jaffe in 1983 and they made such films as "Fatal Attraction" and "The Accused." Jaffe was named president of the former Paramount Communications and in 1992 he made Lansing studio chief.

Lansing, who broke into Hollywood in the late 1960s after being a math teacher in Watts, has been a role model in the film industry. She helped pave the way for other female studio chiefs, including Columbia Pictures' Amy Pascal, Universal Pictures chairwoman Stacey Snider and the late Columbia Pictures head Dawn Steel.

Viacom shares rose 39 cents on the New York Stock Exchange to close at $37.12.