MS-13 (Mara Salvatrucha; also known as simply MS or Mara) is an international criminal gang that originated in Los Angeles, California, US in the 1980s. The gang later spread to many parts of the continental United States, Canada, Mexico, and Central America, and is active in urban and suburban areas. Most members are ethnically of Central American origin (principally El Salvador).

In the U.S., MS-13 has an especially heavy presence in California, the Washington, D.C. metropolitan area, New York City and New Jersey, Boston, Charlotte, North Carolina, and Houston. There is also a presence of MS-13 in Toronto, Canada.

Members of MS are characterised by tattoos covering the body, previously including the face, and by the use of their own sign language. They are notorious for their violence and a subcultural moral code based on merciless retribution. This cruelty of the distinguished members of the "Maras" or "Mareros" earned them a path to be recruited by the Sinaloa Cartel battling against Los Zetas in an ongoing drug war in Mexico.[5][6][7] Their wide-ranging activities have drawn the attention of the FBI and Immigration and Customs Enforcement, who have initiated wide-scale raids against known and suspected gang members, arresting hundreds across the country.