Ioánnis Fokás (Greek: Ιωάννης Φωκάς), better known by the Spanish transcription of his name, Juan de Fuca (born 1536 on the Ionian island of Kefallonia; died there 1602), was a Greek maritime pilot in the service of the Spanish king Philip II, best known for his claim to have explored the Strait of Anián, now known as the Strait of Juan de Fuca.

Fokás's grandfather, Emmanouíl Fokás (Gk: Εμμανουήλ Φωκάς), fled Constantinople at its fall in 1453, accompanied by his brother Andrónikos (Gk: Ανδρόνικος). The two settled first in the Peloponnese where Andrónikos remained, but in 1470 Emmanouíl moved to the island of Kefallonia. Iákovos (Gk: Ιάκωβος), Ioánnis's father, established himself in the village of Valeriáno (Gk: Βαλεριάνο) on the island, and came to be known as "the Valeriáno Fokás" (Gk: ο Φωκάς ο Βαλεριάνος) to distinguish him from his brothers.

It was in this village of Valeriáno that Fokás was born in 1536; little to nothing is known about his life before he entered the service of Spain, some time around 1555.