Thirty Seconds to Mars (commonly stylized as 30 Seconds to Mars) is an American rock band from Los Angeles, California, formed in 1998. The band currently consists of brothers Jared Leto (vocals, guitars, bass guitar, keyboards) and Shannon Leto (drums, percussion). The band went through several former members including, Solon Bixler (guitars, vocals), Matt Wachter (bass guitar, keyboards, vocals), and Tomo Miličević (guitars, bass guitar, violin, keyboards, percussion).

The band's debut album, 30 Seconds to Mars (2002), was produced by Bob Ezrin and released to positive reviews but only to limited commercial success. The band achieved worldwide fame with the release of their second album A Beautiful Lie (2005), which received multiple certifications all over the world, including platinum in the United States. Their next release, This Is War (2009), showed a dramatic evolution in the band's musical style, as they incorporated experimental music as well as eclectic influences. The recording process of the album was marked by a legal dispute with record label EMI that eventually became the subject of the documentary film Artifact (2012). Thirty Seconds to Mars then moved to Universal Music and released the fourth album, Love, Lust, Faith and Dreams (2013), to critical and commercial success. It was followed by America (2018), which polarized critics upon release. As of September 2014, the band had sold over 15 million albums worldwide.