Alexander Martín Callens Asín (born 4 May 1992) is a Peruvian professional footballer who plays as a central defender for Super League Greece club AEK Athens and the Peru national team.

[3] He made his professional debut on 18 April 2010 in a 3–1 loss at León de Huánuco in the Peruvian Primera División,[4] and scored his first goal on 19 June in another away defeat, 2–1 against Inti Gas Deportes.

[7] On 4 December 2014, Callens made his debut with the first team, featuring the entire second half of the 0–0 draw at Real Oviedo in the round of 32 of the Copa del Rey.

[15] Callens converted his attempt in the penalty shootout victory against the Portland Timbers in the MLS Cup 2021 on 11 December, closing the 4–2 score at Providence Park.

[21] Callens won his first cap for Peru on 17 April 2013, replacing Orlando Contreras in the 74th minute of a 0–0 friendly draw with Mexico held in San Francisco.