Matías de los Santos de los Santos (born 22 November 1992) is a Uruguayan professional footballer who plays as a centre-back for Vélez Sarsfield, on loan from Millonarios.
de los Santos began in the academy of Peñarol, prior to heading off to Almagro Baby Fútbol and Ferro Carril Salto of his hometown. After a further youth stint in the ranks of River Plate, de los Santos' senior career began with Danubio in 2013. He made his pro debut on 25 October in the Primera División, as he came off the bench with fourteen minutes left for Camilo Mayada. In May 2014, de los Santos scored his first goal in a draw with Sud América as Danubio won the 2013–14 title. A total of eighty-three appearances, ten of which arrived in the Copa Libertadores/Copa Sudamericana, came in five years alongside three goals.
On 30 June 2017, de los Santos agreed a loan to Millonarios of Colombia's Categoría Primera A. Two goals came as they won the 2017 Clausura. June 2018 saw Millonarios sign de los Santos permanently. He would move clubs again one year later, though did manage to take his overall tally to eighty-three matches and six goals in the preceding months - winning the 2018 Superliga Colombiana in the process. On 18 July 2019, de los Santos secured a one-year loan move to Argentina with Vélez Sarsfield; with a future purchase option.