Exon Gustavo Vallecilla Godoy (born 28 May 1999) is an Ecuadorian professional footballer who plays as a centre-back for Major League Soccer club Columbus Crew on loan from Colorado Rapids. Vallecilla left his home in Esmeraldas, Ecuador at the age of 15 to join Deportivo Cuenca. On 27 November 2016, he made his professional debut for Cuenca against Mushuc Runa S.C. in the Ecuadorian Serie A. In the following season, Vallecilla made one league appearance, while he in the 2018 season made 15. In August 2018 it was reported, that S.D. Aucas had bought 50% of Vallecilla's pass for $80.000, and that he would join the club permanently from the 2019 season, with Cuenca still having a percentage of his pass. Joining Aucas for the 2019 season, Vallecilla only played 167 minutes in the whole season. To get some more games, he was loaned out to Barcelona SC for the 2020 season with an option to buy. He made 15 league appearances for Barcelona, but however, the club decided not to trigger the option to make his stay permanent. Vallecilla then returned to Aucas for the 2021 season. On 5 April 2021, Vallecilla joined MLS side FC Cincinnati on a season-long loan.