The King Cup (sometimes spelled King's Cup) (Arabic: كأس الملك, romanized: kass al-malik), officially known as The Custodian of the Two Holy Mosques' Cup (Arabic: كأس خادم الحرمين الشريفين, romanized: kass khadim al-haramayn al-sharifayn), is the Saudi Arabian football knockout cup competition.
The King's Cup is the second oldest knockout competition in Saudi Arabian football, following the Crown Prince's Cup.
The cup was created in 1957 and was played until 1990. It was re-launched again in 2007 as "King Cup of Champions", and was played by only the top 6 finishers of the Saudi Pro League plus the Crown Prince's Cup and Federation Cup winners. In 2014 it was renamed as "King's Cup", the competition returned to its roots by implementing the old format.