Guillermo Daniel de los Santos Viana (born February 15, 1991) is a Uruguayan footballer who plays as a centre back for Defensor Sporting.
De los Santos started his career playing with Cerro in 2011.
On June 19, 2013, he signed for Club Nacional de Football.
During 2009, De los Santos played with the Uruguay national U20 football team at the 2011 FIFA U-20 World Cup in Colombia.
In 2011, he was named to participate in the Uruguay national U23 team for the 2011 Pan American Games.