LOS ANGELES — Pete Docter is a 6-foot-5 Minnesotan who comes across like Tom Hanks in “Big” and lives in a literal tree house. Jennifer Lee is a 5-foot-3 Rhode Islander and self-described former “flute-playing band nerd” who loves books and is known for her showstopping laugh.

On Tuesday, they became two of the most important people in Hollywood.

As expected, the Walt Disney Company named Ms. Lee to lead its revered Walt Disney Animation Studios and Mr. Docter to lead its Pixar Animation Studios. Both were given the title of chief creative officer. They succeed John Lasseter, 61, who managed both animation studios until earlier this month, when he resigned following complaints about his workplace behavior.

Mr. Docter, 49, is a 28-year Pixar veteran who directed three of its most successful films — “Up,” “Inside Out” and “Monsters, Inc.” — and helped write the screenplays for “Toy Story” and “Wall-E.” He has won two Academy Awards.

Ms. Lee, 46, only got her start in animation in 2012, when she co-wrote the screenplay for “Wreck-It Ralph.” But the following year, she directed, with Chris Buck, the musical sensation “Frozen,” and won an Oscar. She also helped write “Zootopia” and “A Wrinkle in Time” and played a critical role in bringing “Frozen” to Broadway.