Deodato Arellano y de la Cruz (July 26, 1844 – October 7, 1899[2]) was a Filipino propagandist and the first president of the Katipunan, which was founded at his home in Azcarraga Street (Claro M. Recto Avenue today), Manila.

[7] He became an assistant clerk at the weaponry division of the artillery corps[8] of the Spanish military, the Maestranza de Artilleria.

[11] He was also part of the short-lived La Propaganda, a movement founded by his brother-in-law del Pilar and Mariano Ponce, which sought reforms in the political landscape of the Philippines.

[4] In 1892, Arellano and other freemasons, like Andrés Bonifacio, joined La Liga Filipina,[12] which was founded by José Rizal[13] upon his return to the country.

[14] A few days after the founding of La Liga Filipina, Rizal was arrested and detained in Fort Santiago and then later deported to Dapitan island in Mindanao.

[4] Juan de Zulueta helped him to reestablish the Liga and they elected new set of officers with Arellano getting the secretary and treasurer positions.

[4] There are historians who hold that after Arellano was named by Katipunan members who were apprehended by the Spaniards and forced to reveal information, he was eventually arrested too, then tortured and finally abandoned to die.