Three years after withdrawing from the team final of the Tokyo Olympics because of a mental block, a move that prompted critics to call her a loser, a quitter and un-American, Simone Biles on Thursday proved to the world — and to herself — that she was unstoppable.

Wearing a leotard reminiscent of Wonder Woman’s suit, Biles, 27, won the all-around title at the Paris Games, becoming the oldest all-around champion since 1952 and only the third woman — and the first since 1968 — to win two Olympic all-around titles.

The gold was Biles’s ninth Olympic medal, pushing her record total of Olympic and world championship medals to 39 and reaffirming her standing as one of the best athletes of all time.

After Biles learned that she had won, she waved to a crowd that chanted “U-S-A! U-S-A!” and then walked off the raised platform, rested her elbows nearby and exhaled.

“All in all, I’m super proud of my performance tonight and the fight that I had for the last three years, mentally and physically, just to get back competing on a world stage, Olympic Games,” she said, adding, “I couldn’t be prouder.”

Except for an uncharacteristic mistake on the uneven bars, Biles nailed her routines and did so under extraordinary pressure, as Rebeca Andrade of Brazil was having a fantastic night. Andrade, the silver medalist in the all-around in Tokyo, had led the competition after the second of four events.