"Helena" is often considered by journalists to be the band's breakout hit, a contributor to the commercial success of Three Cheers for Sweet Revenge, and an influential track on the emo music genre.

[2] While "Helena" was one of the latter tracks from Three Cheers for Sweet Revenge to be created, the direction that Gerard took the song in influenced how the rest of the album would be produced.

[2] The band began recording the album in 2004 after concluding a short, already scheduled tour in the United Kingdom.

[4] Three Cheers for Sweet Revenge was released on June 8, 2004 through Reprise;[5] "Helena" is the album's opening track.

[9] A live recording of the track, performed at the Starland Ballroom in Sayreville, New Jersey was released on iTunes on May 23.

[12] 16 seconds later, the song fully begins with what Billboard described as a "captivating raucous" of guitars and drums.

[12] The song is generally fairly fast paced, being sung at "manic speed", though each chorus slows the track down temporarily.

[46][16] "Helena"'s commercial success is often credited by journalists as helping popularize emo music in the 2000s,[23][8][47] and has also been considered My Chemical Romance's breakout hit.

[23][8][47] It also contributed to the commercial success of its parent album, Three Cheers for Sweet Revenge, which went on to sell three million units.

[19] Louder's Marianne Eloise wrote that, while "I'm Not Okay (I Promise)" was a more well remembered track from the album, "Helena" was a turning point for the band as their first widespread hit, as well as a song that changed emo on a commercial level.

[8] Bryan Reesman of American Songwriter described "Helena" as a song that not only stood out among the rest of My Chemical Romance's discography, but early 2000s rock music as a whole.

[19] Aliya Chaudhry of Stereogum wrote that "Helena" and its associated music video were cultural touchstones for emo and pop-punk.

[50] While the original focus of the song was a real-world death, the music video shifts over its context to tell the story of a young girl (played by Tracy Phillips) who died, with Gerard Way standing in the pulpit.

Throughout the music video, it cuts between shots of the band performing in the church to the funeral attendees participating in a dance number.

[48] After a while, the girl rises from her coffin and begins to dance through the church aisle, interacting with the attendees and at one point grabbing the camera to join her.

Eventually, she collapses back into her casket, and is carried out of the church in the rain[8] by six pallbearers: the band's five members, plus one fan.

[58] During the band's 2007 tour to promote their third studio album The Black Parade (2006), "Helena" was typically the last song performed on the standard set list.