Alejandro Matías Luis Ignacio Reyes Cotapos (24 February 1825 – 8 January 1884) was a Chilean lawyer and politician.

Throughout his political career, Reyes remained allied with Manuel Montt and Antonio Varas, whose supporters formally established the National Party in 1857.

Reyes won his first parliamentary election the next year, taking a seat in the Chamber of Deputies as a representative of Los Ángeles and Yungay.

Upon his return from exile in Europe in 1862, Reyes became a diplomat and helped reach treaties with Ecuador and Costa Rica.

Later, Reyes aided in the drafting of the legal codes regulating commerce, civil actions, and criminal activity.