Gustavo Leonardo Cuéllar Gallegos (born 14 October 1992) is a Colombian professional footballer who plays as a midfielder for Campeonato Brasileiro Série A club Grêmio and the Colombia national team.

Cuéllar formed a key part of the 2013 squad that finished runners-up in 2013 Torneo Finalización, losing in the finals to Atlético Nacional.

On June 28, 2017 in a Copa do Brasil match against Santos at Ilha do Urubu, Cuéllar scored his first goal for Flamengo in a 2-0 victory.

[5] Only after Flamengo signed compatriot Reinaldo Rueda[6] as head coach did Cuéllar manage to take a starting position in the midfield.

[9] In August 2019, Cuéllar was suspended from club activities indefinitely for refusing to travel with the team for the following league match, citing family matters.

[14] Gustavo played for Colombia U17 in the 2009 FIFA U-17 World Cup, he appeared in all seven matches and scored two goals, both against Gambia in a 2–2 draw,[15] as the team finished the tournament in fourth place.