In Greek mythology, Capys was

1. a son of Assaracus and Aigesta or Themiste and father of Anchises and so grandfather of Aeneas
2. the Trojan, who warned not to bring the Trojan horse into the city
3. a descendant of Aeneas and king of Alba Longa

The first one, or a different Capys, founded the city of Capua. (Virgil X, 145)