Created in 1998 by Jared Leto and his brother, Shannon, 30 Seconds to Mars began as a small family project. Things began to speed up quickly, however, and Matt Wachter later joined the band as bassist and keyboard player. After a small revolving door of guitarists (as the band's first two guitarists, Kevin Drake and Solon Bixler, left the band due to issues primarily related to touring), the three auditioned Tomo Milicevic to round out the band's roster.

According to an interview from Virgin Records, the band's name "actually comes from a thesis that [the band] found online [that] was written by a former Harvard professor. And one of the subsections of the thesis was titled 'thirty seconds to mars' and he goes on to talk about the expediential growth of technology that relates to humans and saying that we are quite literally thirty seconds to mars. What it means to us is, we thought it best described our music, in short."

Although Leto is a Hollywood actor, he originally preferred not to use this information to promote the band; in fact, the band used to refuse to play at venues that used his fame to promote shows.

30 Seconds to Mars' first, self-titled, album, produced by Bob Ezrin, was released in 2002 to mixed reviews and achieved sales of just over 100,000. The band's second album, A Beautiful Lie, was released on August 30, 2005. For this effort, the band traveled (during the course of three years) to four different continents, including five different countries, to perfect their sound and also to allow for Jared's film career. The album was produced by Josh Abraham, whose producing credits also include Orgy, Velvet Revolver, and Linkin Park.

Because A Beautiful Lie was leaked five months before its release, the band decided to include two bonus tracks: "Battle of One" (an original song that was also set to be the album's title track when it was first announced) and "Hunter" (a cover of the Björk song of the same name). To further promote the album, the band also enclosed "golden tickets" in 12 copies, which grant their owners access to any 30 Seconds to Mars concert free of charge, along with backstage access.

On March 1, 2007, bassist Matt Wachter announced his departure from the band live on stage during the band's El Paso, Texas "Taste of Chaos" set. This was confirmed the following day with a statement on the band's website.[3] He has since been replaced by Tim Kelleher (not the actor), who has been seen playing at the band's concerts. It is unknown if this is a temporary or permanent change.
[taken from wikipedia]