Pío Valenzuela y Alejandrino was a Filipino physician and revolutionary leader. At the age of 23, he joined the society of Katipunan, a movement which sought the independence of the Philippines from Spanish colonial rule and started the Philippine Revolution. Together with Andrés Bonifacio and Emilio Jacinto, they formed the secret chamber of the society called Camara Reina. He took charge of the publication of Ang Kalayaan, Katipunan's first and only official publication. He was the one who tried to convince the exiled José Rizal to join the revolutionary movement.

The Katipunan, officially the Kataastaasan Kagalang-galang na Katipunan ng mga Anak ng Bayan and abbreviated as the KKK, was a revolutionary organization founded in 1892 by a group of Filipino nationalists Deodato Arellano, Andrés Bonifacio, Valentin Diaz, Ladislao Diwa, José Dizon, and Teodoro Plata. Its primary objective was achieving independence from the Spanish Empire through an armed revolution. It was formed as a secret society before its eventual discovery by Spanish authorities in August 1896. This discovery led to the start of the Philippine Revolution.