David John Sincock (born 1 February 1942) is a former Australian cricketer who played in three Test matches from 1964 to 1966.

Nicknamed "Evil Dick" by his teammates, Sincock was called "one of the most interesting bowlers I have ever played against" by Garry Sobers, who claimed that Sincock turned the ball more than any other bowler he had faced and had an unreadable googly.^[1] However, Sobers noted that Sincock was too inconsistent, bowling an over of long hops and full tosses for every unplayable delivery.^[1] His last Test was against England in the Third Test at Sydney in 1965-66, Sincock was hit for 0/98, but made a fighting 29 and 27 as Australia suffered their worst home defeat in over 50 years. The selectors promptly dropped five players including Sincock and the stand-in captain, Brian Booth, neither of whom played for Australia again.

Sincock dropped out of first-class cricket after the 1965–66 season, moving to Sydney where he played for Sydney Grade Cricket club Northern District.^[2] He later said, "I definitely didn't want to be a professional sportsman ... Once I'd got a guy out I couldn't really see the point in getting him out again next week."^[3] He became a successful business executive.