John Stefan Medina Ramírez (born 14 June 1992) is a Colombian professional footballer who plays for Liga MX club Monterrey and the Colombia national team.

[4] He was a regular starter for the team throughout the entire 2014-15 season and was named in the team's starting lineup for the inaugural game at the BBVA Bancomer stadium, although throughout the Apertura 2015 his performance was frequently criticized and he was eventually benched by 18-year old rookie Cesar Montes in the centre-back position.

On 28 November 2015, Rayados de Monterrey announced that Medina had been transferred to Pachuca on a season-long deal, in exchange for Miguel Ángel Herrera.

He won the league title in May 2016 after Pachuca defeated his former club Monterrey 2–1 on aggregate, he was a starter throughout the entire season and was regularly deployed as a right-back, his loan was extended for the entire 2016-17 season during which he won the 2016-17 CONCACAF Champions League in April 2017 against Tigres UANL, playing as a substitute in both games at the Finals.

Medina was regularly called on to the squad after his second cap, but suffered an ankle injury on April 24, 2014, thus forcing him to miss out on the 2014 FIFA World Cup.