King Guardia XXI is the ruler of the Kingdom of Guardia in 600 A.D. in Chrono Trigger. He is the 21st King of Guardia and the ancestor of King Guardia XXXIII as well as Princess Nadia (also known as Marle).
As the war escalates, King Guardia is wounded in the battle against Magus' army. When Crono and his party pay him a visit, the King explains that they had to rely on the "legendary hero" everyone was talking about since Cyrus was nowhere to be found. He tells Crono the "legendary hero" was on the Southwestern continent.
King Guardia is seen in a flashback sequence. He watches Cyrus leave the castle to fight Magus' army.
Crono's party meets with King Guardia XXI after the Rainbow Shell has been recovered.