Arsenio H. Lacson (December 26, 1911 — April 15, 1962) was a Filipino journalist and politician who gained widespread attention as Mayor of Manila from 1952 to 1962. An active executive likened by Time Magazine and the New York Times to New York's Fiorello La Guardia, he was the first Manila mayor to be reelected to three terms. Nicknamed "Arsenic" and described as "a good man with a bad mouth", Lacson's fiery temperament became a trademark of his political and broadcasting career. He died suddenly from a stroke amidst talk that he was planning to run in the 1965 presidential elections.
It was only in 1951 that the office of Manila mayor became an elective position, following the amendment of its city charter. Representative Lacson successfully unseated incumbent Manila mayor Manuel de la Fuente in the first ever mayoralty election in the city. He assumed the office of mayor on January 1, 1952. He was re-elected in 1955 and 1959. He immediately became known as a tough-minded reformist mayor, and in the 1950s, he and Zamboanga City mayor Cesar Climaco were touted as exemplars of good local governance. Climaco, in fact, was praised as "The Arsenio Lacson of the South".
At the time Lacson assumed office, Manila had around 23.5 million pesos in debt, some of which had been contracted thirty years earlier, and had no money to pay its employees. Within three years, the debt had been reduced in half, and by 1959, the city had a budget surplus of 4.3 million pesos and paid its employees twice the amount earned by other local government employees. By that time, Lacson claimed that the income earned by Manila for the Philippines supported 70% of the salaries of the national government officials and members of Congress, as well as 70% of the expenses of the Armed Forces of the Philippines.
In 1953, Lacson actively campaigned for Nacionalista presidential candidate Ramon Magsaysay, who would go on to defeat the incumbent Quirino. After President Magsaysay's death in a plane crash months before the 1957 presidential elections, Lacson claimed that Magsaysay had offered to name him as the Nacionalista candidate for Vice President, in lieu of incumbent Vice-President Carlos P. Garcia. According to Lacson, he declined the offer, telling Magsaysay "the time has not yet come".