Glassjaw is an American post-hardcore band from Hempstead, New York. It was formed in 1993 by vocalist Daryl Palumbo and guitarist Justin Beck. The band is known for their intense live shows, as well as their frequent line-up changes. Despite their limited commercial success and small discography, they are considered to be one of the most influential bands in the progression of the underground music scene in the eastern United States and United Kingdom for the post-hardcore genre.

After recording a number of EPs and demos throughout the 1990s, Glassjaw came to the attention of producer Ross Robinson, who helped the band secure a deal with Roadrunner Records. Robinson went on to produce Glassjaw's debut album, Everything You Ever Wanted to Know About Silence (2000), which helped the band cement a following in the United Kingdom. After parting ways with Roadrunner following a feud, Glassjaw signed with Warner Bros. Records, who issued the group's second outing Worship and Tribute (2002). The album reached number 82 on the Billboard 200 chart and brought Glassjaw to mainstream attention, although its supporting tour was negatively affected by Palumbo's struggles with Crohn's disease around this time, leading to the cancellation of several dates. Although the group continued to tour semi-regularly, Glassjaw's studio activity was sporadic for the rest of the 2000s whilst Palumbo and Beck focused other projects.

After parting ways with Warner Bros., Glassjaw self-released a series of 7" singles throughout late 2010, which were later compiled into the EP Our Color Green (The Singles) in January 2011. One month afterwards, the group released another EP, Coloring Book. In 2017, Glassjaw released their first album in 15 years, Material Control, through Century Media Records. During 2022, the band performed a series of concerts commemorating the 20th anniversaries of the band's first two albums.