After running the world's largest video site for the last nine years. She'll be replaced by Neal Mohan, her longtime lieutenant.

Wojcicki is officially Google employee No. 16, and a year before she was hired, famously rented her parent's garage to Google founders Larry Page and Sergey Brin, where they set up their first office. Wojcicki joined Google when it had no revenue and has been at the company forits entire history.

Her first role was Google's first marketing manager in 1999, and in 2003 she became Google AdSense's first product manager. Wojcicki is credited with the idea to buy YouTube in 2006 and managed that $1.65 billion acquisition as well as the $3.1 billion purchase of DoubleClick the next year. By 2014 she was CEO of the world's biggest video site.

In a letter sent to YouTube's employees, Wojcicki said she was leaving in order to "start a new chapter focused on my family, health and personal projects I'm passionate about."

During her tenure, YouTube became increasingly important to the business for Google, which bought the site in 2006, and Alphabet, the holding company that houses both of them: In 2022, YouTube generated $29.2 billion in ad sales -- more than 10 percent of Alphabet's total revenue.