Mariano Álvarez (March 15, 1818 – August 25, 1924) was a Filipino general and politician. An ally of Andres Bonifacio, he was designated Second Supremo of the Katipunan during the Philippine Revolution.
Alvarez had been an active member of the Katipunan, the anti-Spanish secret society founded by Andres Bonifacio in 1895. In early 1896, Álvarez was elected president of the Magdiwang faction. He helped facilitate growing membership of the Katipunan in Cavite. When the revolution burst in 1896, he led Filipino forces in several battles against the Spanish army in Cavite. His efforts helped liberate most towns in Cavite from Spanish control within weeks from the start of the revolt.
In December 1896, Bonifacio designated Álvarez as a general and the Second Supremo of the Katipunan, effectively the second-in-command of the group.
After losing an internal power struggle with Emilio Aguinaldo for command of the revolutionary forces, Bonifacio was executed in 1897. Alvarez was aggrieved by Bonifacio's death, and, like Emilio Jacinto, refused to join the forces of Aguinaldo, who had then retreated to Biak-na-Bato in Bulacan.