Bobby Unser -- who won the Indianapolis 500 race THREE TIMES during his illustrious career -- died Sunday at his home in New Mexico.
He was 87.
Officials at Indianapolis Motor Speedway say Unser died of natural causes -- but did not get into specifics.
Unser -- brother of fellow Indy 500 champ Al Unser -- is survived by his wife, Lisa, along with 2 sons Bobby Jr. and Robby and 2 daughters Cindy and Jeri.
Bobby Unser was a titan of the sport -- winning The Greatest Spectacle in Racing in 3 consecutive decades .