| Guillermo de los Santos | |
| Fullname: | Guillermo Daniel de los Santos Viana |
| Birth Date: | 15 February 1991 |
| Birth Place: | Montevideo, Uruguay |
| Position: | Centre back |
| Currentclub: | Defensor Sporting |
| Clubnumber: | 3 |
| Years1: | 2011–2013 |
| Caps1: | 60 |
| Goals1: | 9 |
| Years2: | 2013–2015 |
| Caps2: | 32 |
| Goals2: | 0 |
| Years3: | 2015–2018 |
| Caps3: | 44 |
| Goals3: | 1 |
| Years4: | 2017 |
| Clubs4: | → Universidad Católica de Quito (loan) |
| Caps4: | 15 |
| Goals4: | 0 |
| Years5: | 2018–2022 |
| Caps5: | 112 |
| Goals5: | 3 |
| Years6: | 2022 |
| Caps6: | 25 |
| Goals6: | 0 |
| Years7: | 2023– |
| Caps7: | 26 |
| Goals7: | 2 |
| Nationalyears1: | 2011 |
| Nationalcaps1: | 3 |
| Nationalgoals1: | 0 |
| Nationalyears2: | 2011 |
| Nationalcaps2: | 3 |
| Nationalgoals2: | 0 |
| Club-Update: | 15 November 2023 |
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. He made his debut on 20 February 2011 against Defensor Sporting. 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.