Saint Leonidas (or Leonides) refers to several Christian martyrs:
An Egyptian who died in the Diocletianic Persecution (feast day 28 January)
A companion of St. Diomedes (feast day 2 September)
A 4th-century Eastern Orthodox martyr (feast day 8 August)
A sixth-century Bishop of Athens (feast day 15 April)
One of seven companions, including Callistus and Charysius, martyred in Corinth (feast day 16 April)
Leonides of Alexandria, father of Origen (feast day 22 April)