Santiago Lionel Ascacíbar (born 25 February 1997) is an Argentine professional footballer who plays as a defensive midfielder for Estudiantes.

He then moved to Bundesliga team VfB Stuttgart in 2017, developing a reputation as a natural leader alongside criticism for his temperament.

[2] He completed a transfer to Hertha BSC in January 2020 after Stuttgart had suffered relegation the previous season, with manager Jürgen Klinsmann describing him as "one of the best defensive midfielders in the Bundesliga".

[9] After recording impressive performances in his first four years in AFA youth divisions, the team's youth football coordinator Hermes Desio promoted him to the reserves for the first time in late 2014, and Ascacíbar made his debut in a match against the reserves of Rosario Central away at the Estadio Gigante de Arroyito.

[10][11] Already in early 2015, he represented Estudiantes at the Frenz International Cup in Malaysia and Indonesia with a team consisting of players born in 1997 and 1998.

[11] That same year, and on the recommendation of former international Juan Sebastián Verón who was now president of the club, Ascacíbar finished his secondary studies at the Colegio de Estudiantes and enrolled in Anthropology at the National University of La Plata,[11] despite not being able to regularly attend classes due to his professional debut with the first team.16In this sense, Ascacibar was seen as the antithesis of the typical professional footballer: he still lived with his parents and siblings and lead a life away from lavishness, valuing an education.

But you don't have to judge that either, because everyone is responsible for what they do and everyone is free in their life to do what they want.On 8 February 2016, Ascacíbar made his professional debut for Estudiantes, playing the entire match against Lanús in the Argentine Primera División which ended in a 1–0 loss.

[30][31] Ascacíbar returned to the pitch on 30 January 2021 under new manager Pál Dárdai, playing 89 minutes of the 3–1 defeat to Eintracht Frankfurt.

Despite scoring the opening goal against Borussia Mönchengladbach in an eventual 2–2 draw, he sneered when substituted off in the second half, which coach Dárdai criticised afterwards.

[35] Ahead of the 2021–22 season, in a pre-season friendly against Liverpool, Ascacíbar suffered a concussion after colliding with opposing goalkeeper Caoimhín Kelleher after scoring the opening goal in a 4–3 victory.

[43] With the U20 team, Argentina finished in 4th place at the 2017 South American Youth Championship, thus qualifying to the 2017 U20 FIFA World Cup.