Susan Wojcicki, who helped turn Google from a start-up in her garage into an internet juggernaut and became one of Silicon Valley’s most prominent female executives with her leadership of YouTube, died on Friday. She was 56.

Her death was confirmed by her husband, Dennis Troper, who wrote on Facebook on Friday that she had been living with lung cancer.

A YouTube spokesman confirmed the date of her death.

Sundar Pichai, Google’s chief executive, announced her death in a statement on Friday. “She is as core to the history of Google as anyone, and it’s hard to imagine the world without her,” he said.

A full obituary will follow.