Luis Crisologo "Chavit" Singson (Tagalog pronunciation: [ˈtʃavɪt ˈsiŋson]; born June 21, 1941) is a Filipino businessman and politician who last served as the mayor of Narvacan, Ilocos Sur from 2019 to 2022. He was also the governor of the province of Ilocos Sur, starting from 1972 until 1986, again from 1992 until 2001, again from 2004 to 2007, and again from 2010 until 2013. He was also the Deputy National Security Adviser for the Philippine government (2008).

Singson ran for senator under Team Unity in 2007, but lost.

Chavit Singson was born on June 21, 1941, in Vigan, Ilocos Sur. He is second eldest among the seven children of José Singson and Caridad Crisólogo. He studied in Colegio de San Juan de Letran in Manila and finished his Commerce degree.

Both his paternal (Singson) and maternal (Crisologo) families have dominated the political environment of the Ilocos region for generations. Although many members of both families, such as Chavit are related to one another, the two families have shared a bitter feud which reached its apex in the 1960s and 1970s, when shootings and political intimidation were rampant in the Ilocos region. Chavit considered his uncle, Floro Crisologo as a mentor, but eventually had a severe falling out with his cousin and once-confidant Vincent Crisologo who was Floro's son and there were many bloody encounters between the two. It is currently stated by both sides that tensions have eased.

In October 2000, Singson publicly accused his friend and then-President Joseph Estrada of plotting to assassinate him after a falling-out over the share of jueteng and tobacco revenues. He also confessed to being Estrada's personal collector of such revenues in Luzon. Singson's revelations helped trigger protests against Estrada, leading to his impeachment and overthrow in the Second EDSA Revolution in January 2001.

Singson secured a spot as a candidate for the 2007 Philippine senatorial elections after siding with the administration of President Gloria Macapagal-Arroyo, despite being former friends with the former president Joseph Estrada. After losing the elections, Singson was appointed Deputy National Security Adviser on September 5, 2008, by Arroyo. He mended his friendship with Estrada sometime later. He was a member of Lakas–CMD until 2010.

In the 2010 Philippine presidential election he endorsed the Nacionalista presidential nominee Manny Villar and in the 2013 elections he supported the candidates of the United Nationalist Alliance.

Singson has served as governor of Ilocos Sur for multiple terms. From 2019 to 2022, he served as mayor of Narvacan under the local party Bileg Ti Ilokano.