Al Unser Sr. and Al Unser Jr. are a father-son duo of American race car drivers. Al Unser Sr., also known as 'Big Al' or 'Al the Elder, ' is a four-time Indianapolis 500 winner and three-time IndyCar Series champion. His son, Al Unser Jr., also known as 'Little Al' or 'Al the Younger, ' is a two-time Indianapolis 500 winner and two-time IndyCar Series champion. Together, they are the only father-son duo to have both won the Indianapolis 500.