Thirty Seconds to Mars (commonly stylized as 30 Seconds to Mars) is an American rock band based in Los Angeles, California, formed in 1998 by brothers Jared Leto and Shannon Leto. Originally conceived as a musical project for the Leto brothers, the band's lineup later expanded to include members Matt Wachter and Tomo Milicevic. The group's self-titled debut album was released in 2002, garnering positive reviews and showcasing a blend of alternative sounds, including neo-progressive rock, hard rock, synthrock, and post-grunge.

The band gained widespread recognition with their second album, A Beautiful Lie, released in 2005, which achieved multiple certifications worldwide. Their subsequent album, This Is War (2009), marked a notable evolution in their musical style, incorporating experimental influences while also being surrounded by a legal dispute with their label, EMI. This struggle culminated in the documentary film Artifact (2012), documenting their experiences during this tumultuous period.

In 2013, the group transitioned to Universal Music and released their fourth studio album, Love, Lust, Faith and Dreams, which was met with critical acclaim and commercial success. The album featured prominent singles such as "Up in the Air" and "Conquistador." By this time, Thirty Seconds to Mars had established a reputation for energetic live performances and an eclectic fusion of musical genres, supported by philosophical and spiritual themes in their lyrics.

Throughout their career, Thirty Seconds to Mars has achieved significant commercial success, selling over 15 million albums worldwide as of September 2014. Their dedication to environmental sustainability was showcased during their 2006 Welcome to the Universe tour, in which they implemented eco-friendly practices. The band also made history by earning a Guinness World Record for the "Longest Concert Tour," having performed over three hundred concerts in a span of approximately two years.

As the Leto brothers remained the consistent core of the band amidst various lineup changes, their collaboration has continuously pushed the band's creative boundaries. In recent years, Thirty Seconds to Mars has released new music, including their 2018 album America and their 2023 project It's the End of the World but It's a Beautiful Day. The latter album included the lead single "Stuck," released in May 2023.

In celebration of their musical journey, Thirty Seconds to Mars announced a commemorative 20th-anniversary edition of their debut album in August 2022 and continued to engage with fans through live performances, including an appearance at the When We Were Young festival in October 2023. Always evolving, the band’s blend of rock and experimental music continues to resonate with audiences around the world.