The WWE said Hellwig died on Tuesday but did not give any other details.
Hellwig was one of pro-wrestling's biggest stars in the late 1980s. He beat Hulk Hogan in a memorable match at Wrestlemania in 1990.
He was in the spotlight again earlier this week, making appearances at the latest Wrestlemania in New Orleans and on Monday Night Raw, and being inducted into the WWE Hall of Fame.
"WWE is shocked and deeply saddened to learn of the passing of one of the most iconic WWE Superstars ever, The Ultimate Warrior," WWE said in a statement, adding: "We are grateful that just days ago, Warrior had the opportunity to take his rightful place in the WWE Hall of Fame."
WWE chairman Vince McMahon tweeted: "We are all so sad the Ultimate Warrior has passed away. Our heart is with his wife Dana and his two daughters."