Íñigo Fernández de Velasco (1462–17 September 1528), 2nd Duke of Frías, Grandee of Spain, and Constable of Castile (Spanish: Don Íñigo Fernández de Velasco y López de Mendoza, segundo duque de la villa de Frías, cuarto conde de Haro, octavo Condestable de Castilla, mayorazgo y señor de la Casa de Velasco, Caballero del Toisón de Oro), was a Spanish nobleman.
Fernández de Velasco was the son of Pedro Fernández de Velasco and of Mencía de Mendoza y Figueroa. He inherited the titles from his older brother Bernardino, who had no legitimate male issue. He married María de Tovar, Lady of Berlanga, with whom he had six children.
He took part in the Revolt of the Comuneros, leading the royalist army to crushing victory at the Battle of Villalar.