"Santo" (transl. "Saint") is a song recorded by American singer Christina Aguilera and Puerto Rican rapper and singer Ozuna for her ninth studio and second Spanish-language album, Aguilera (2022). It was written by Aguilera and Ozuna, alongside DallasK, Gale, and Josh Barrios, while the production was handled by DallasK, Rafa Arcaute, Federico Vindver, co-produced by Afo Verde, and its vocal production was handled by Jean Rodríguez. It was released by Sony Music Latin as the album's third single on January 20, 2022. It is the third consecutive and final single to be featured on the album's first part, La Fuerza (transl. The Strength).

"Santo" is a reggaeton song with urbano and cumbia influences. Lyrically, the song is about two people who are willing to do anything for each other. It received positive reviews from music critics, who praised Aguilera's vocals and the song's rhythm and catchiness. "Santo" achieved commercial success mainly in Latin American territories, reaching top 10 in Guatemala, El Salvador, Panama, Puerto Rico, and Peru. It also received a platinum certification (Latin field) from the Recording Industry Association of America (RIAA), and was nominated for Best Urban Fusion/Performance at the 23rd Annual Latin Grammy Awards.

"Santo" was created for Aguilera's follow-up album to Mi Reflejo (2000) during recording sessions in 2021. Aguilera sought out to pay tribute to the music of Latin America with the album's sound, paying tribute to several genres from the region. "Santo" is a reggaeton song, a genre of music originating from Panama and Puerto Rico which falls under the urbano music category. The song contains influences of Colombian cumbia, and through its use of drums and percussion instruments such as the maraca, the song features the sound of rumba. It is written in the key of A minor, with a moderately fast tempo of 96 beats per minute.

Lyrically, "Santo" tells the story of two people who are "dying for each other" and are ready to commit every sin possible. In the chorus, Aguilera calls her lover a "Saint" inviting her lover to "come and save" her, While Ozuna calls her "more dangerous than the impact of an assault rifle".

Upon its release, the single received positive reviews from music critics. Billboard considered "Santo" an "infectious perreo", and praised the song for its "catchy hook", Ozuna's "crisp, sugary vocals" and Aguilera's vocal range. Liz Calvario‍ of Entertainment Tonight called "Santo" "the hottest song of the year", and Lucas Villa from Rolling Stone labelled it as a "sexy" reggaeton song. Writing for Remezcla, Isabella Vega thought that "Aguilera has embodied the pop-based vein of reggaeton with the absolute banger, 'Santo'". In his review for Atwood Magazine, Josh Weiner found the song "fiesta-ready" and cheered its "pure Latin production". He also described Ozuna's singing as "spicy". BroadwayWorld's Michael Major praised Aguilera's "unmatched vocals in full force" and thought that the song's "Latin rhythms create the perfect flow that makes an instant hit."

According to El Tres, the song is "driven by a contagious reggaetón rhythm". Lideny Villatoro of Univision opined that "Santo" is a perreo-influenced "jam" and "it's a sin not to want to dance to its rhythm". She also called the song a "potential hit". Pip Ellwood-Hughes from Entertainment Focus considered "Santo" "undeniably catchy" and the "EP's strongest moment". He believed that the single's "pumping beat will see it spreading throughout the clubs in Latin America, and across the globe". A reviewer from Monitor Latino shared the same sentiment, calling the song "very rhythmic", and noting that it will make "everyone dance to it". Shirley Gómez of ¡Hola! labelled "Santo" as a "powerful interpretation that honors Latin and Afro-Caribbean rhythms". Writing for NEIU Independent, Enrique Cerros named the song "spicy" and thought that it "screams club banger". Aldo Magallanes of a daily newspaper El Siglo de Torreón called the song "a perfect fusion" and "a powerful performance that, accompanied by Latin rhythms, becomes an instant hit".

American Songwriter's Jacob Uitti positioned "Santo" at number five on his list of the top 10 Christina Aguilera songs. In July 2022, Billboard called the song one of "the best Latin collaborations of the year (so far)".

In the United States, "Santo" reached number 24 on Billboard's Hot Latin Songs. The song fared better on the airplay charts, reaching number 12 on the Latin Airplay chart, and number three and seven on the Latin Pop Airplay and Latin Rhythm Airplay charts respectively. It received a platinum certification by the Recording Industry Association of America (RIAA) in the Latin field.