Gian Louis Clavell López (born November 26, 1993) is a Puerto Rican professional basketball player for Piratas de Quebradillas of the Baloncesto Superior Nacional. He played three seasons of college basketball for the Colorado State Rams, earning Mountain West Conference Player of the Year honors in 2017. He also represents the Puerto Rican national team.

Clavell played college basketball for Northwest Kansas between 2012 and 2014 and then Colorado State between 2014 and 2017. He was named Mountain West Conference Player of the Year in 2017, becoming the first CSU Ram to win the award.

After graduating from college, Clavell had a three-game stint with Brujos de Guayama in Puerto Rico prior to the 2017 NBA draft. After going undrafted, he joined the Miami Heat for the 2017 NBA Summer League. On July 23, 2017, he signed a partially-guaranteed deal with the Dallas Mavericks to join the preseason roster. His contract would later be converted to a two-way deal, meaning throughout his time with the Mavericks, he would split playing time between Dallas and their NBA G League affiliate, the Texas Legends. He played seven NBA games before being waived by the Mavericks on November 17, 2017.

In January 2018, Clavell joined Sakarya BB of the Turkish Super League (BSL).

In July 2018, Clavell joined the Golden State Warriors for the 2018 NBA Summer League. On August 3, 2018, he signed a one-year deal with Movistar Estudiantes of the Liga ACB.

In July 2019, Clavell joined the Portland Trail Blazers for 2019 NBA Summer League. On December 11, 2019, he signed with Frutti Extra Bursaspor of the Turkish BSL. In 12 games to finish the 2019–20 season, he averaged 18.7 points, 3.5 rebounds, 1.7 assists and 1.6 steals per game.

On October 24, 2020, Clavell signed with Avtodor Saratov of the VTB United League. In April 2021, he joined Promitheas Patras of the Greek Basket League. He appeared in 11 games to finish the season.

On August 11, 2021, Clavell signed with Budivelnyk Kyiv of the Ukrainian Basketball SuperLeague.