The title of champion, or leading, sire of racehorses in Great Britain and Ireland is awarded to the stallion whose offspring have won the most prize money in Britain and Ireland during the flat racing season. The current (2022) champion is Dubawi, who earned his first title after finishing runner-up multiple times. Unlike the similar title for leading sire in North America, the stallion in question does not need to have resided in Great Britain or Ireland during his stud career, although the vast majority have done so. Northern Dancer is the most notable example of a North American-based stallion who won this title. The Northern Dancer sire line has dominated the list for the last several decades, mostly through his son Sadler's Wells (14 titles) and grandson Galileo (12 titles).

Records

Most championships:

Champion sires 1721–1997

Champion sires since 1998

Top sire lines

Excluding any championships by the foundation stallions themselves, the following sire-lines have produced champion sires (1721–2016):