Barrio 18, also known as the 18th Street Gang or Mara 18, is a multi-ethnic street gang that originated in Los Angeles. It has members in the United States, Mexico and Central America.

In El Salvador, Barrio 18 is a rival of MS-13. President Nayib Bukele has cited the two gangs as a reason for the state of emergency and mass-arrest campaign launched in 2022.