Who was the oldest number one ranked golfer?

Vijay Singh was 41 years, 6 months and 2 weeks old when he first became world number one on September 5, 2004. He was 42 years, 3 months and 3 weeks old when he last held the position on June 11, 2005.

More about Vijay Singh

Vijay Singh was born on 22 February 1963 in Lautoka, Viti Levu, Fiji.

His nickname is “The Big Fijian”; he's 6 ft 2 in tall (1.88 m).

Singh has won 34 events on the PGA Tour, including three major championships, the 2000 Masters and the PGA Championships in 1998 and 2004.

He was inducted to the World Golf Hall of Fame in 2006.