Iñaki Villanueva Martínez (born 10 February 1991) is a Spanish rugby sevens player.
He competed for Spain at the 2016 Summer Olympics in Brazil.
He was part of the squad that won the 2016 Men's Rugby Sevens Final Olympic Qualification Tournament in Monaco and he played the Olympic tournament.
His brother is Alejandro Villanueva, an American football offensive tackle for the Pittsburgh Steelers of the National Football League (NFL).
Alejandro was also a captain in the United States Army, with whom he served as an Army Ranger, decorated with a Bronze Star for valor after serving three tours of duty in Afghanistan.
He previously played college football for the Army Black Knights.