William "Billy" Mackesy (8 April 1880 - 12 November 1956) was an Irish hurler and Gaelic footballer who played as a forward for the Cork senior teams.Born in Buttevant, County Cork, Mackesy first arrived on the inter-county scene at the age of twenty-one when he first linked up with the Cork senior football team.
He made his debut during the 1901 championship.
Mackesy immediately became a regular member of the starting fifteen and won one All-Ireland medal and one Munster medal.
He later joined the Cork senior hurling team, with whom he won All-Ireland medal and one Munster medal.
Mackesy was an All-Ireland runner-up on four occasions.
At club level Mackesy was a seven-time championship medallist as a footballer with Lees.
As a hurler he also won six championship medals with Blackrock.
Throughout his career Mackesy made a combined total of 43 championship appearances.
He retired from the inter-county scene following the conclusions of the respective 1912 championships.
Mackessy is one of only fifteen players to have won All-Ireland medals in both codes.