Alex Chesiro Masai (born 5 February 1997) is a Kenyan long-distance runner based in the United States.

[4] He was recruited to the Monroe Mustangs track and field program where he finished 8th at the 2017 NJCAA national cross country championships.

In 2018, Masai transferred to join the Hofstra Pride track and field team in the NCAA Division I.

[7] In August 2021, Masai signed with the HOKA One One Northern Arizona Elite professional running group.

[3] He attended Mang'u High School in Thika, Kenya where he played handball and ran track, often training with his sister.