Menomena are an experimental rock band from Portland, Oregon, made up of Brent Knopf on guitar, keyboards, glockenspiel; Justin Harris on bass, guitar, baritone sax and alto sax; and Danny Seim on percussion. All members of the band share singing duties.

The band formed in late 2000, when Knopf graduated from Dartmouth College and returned to Portland to collaborate with Harris and Seim. They played their first show in July 2001, at The Meow Meow, a now-defunct all ages venue in Portland.

They self-released their debut album, I Am the Fun Blame Monster!, on May 20, 2003. The album was elaborately packaged in an 80-page flipbook that Seim designed and individually hand-assembled. It later received nationwide distribution through FILMguerrero in 2004. The title is an anagram for The First Menomena Album.

In 2005, Under an Hour was released as a three-track album of instrumental music written for and performed with Monster Squad, an experimental dance company based in Portland.

In August of 2006, Menomena signed with Barsuk Records although the band still maintains a relationship with their old label, FILMguerrero. It was stated that FILMguerrero would still be involved in their old catalog and future vinyl releases.

Menomena released their next album in 2007, titled Friend and Foe. It received relative critical acclaim -- while some websites like Pitchfork Media praised the album for its effective modular pop, others like PopMatters criticized it for presenting a sense of feigned maturity. Their record release show was held in their home town of Portland, Oregon. The packaging was designed by Knopf and features artwork by graphic novelist/cartoonist Craig Thompson, consisting of die-cut shapes, decoder rings, and hidden messages. It was nominated for "Best Recording Package" at The Grammy Awards.

The band's name was chosen for "the way it rolls off the tongue, sexually, or something" and has no specific meaning, although it is often assumed to refer to the Piero Umiliani song "Mah Nà Mah Nà", a staple of The Muppet Show. A recent audioclip from SpotDJ had Brent stating that the band name was a contraction of the words "Men" and "Phenomena". This is most likely a joke.

The band uses a computer program called the Digital Looping Recorder, or Deeler for short, in the song writing process - it was programmed by band member Brent Knopf. Drummer Danny Seim explains the process, "First, we set the tempo of the click, which is played through a pair of headphones. We then take turns passing a single mic around the room. One of us will hold the mic in front of an instrument, while another one of us will lay down a short improvised riff over the click track. We usually start with the drums. Once the drums begin looping, we throw on some bass, piano, guitar, bells, sax, or whatever other sort of noisemaker happens to be in the room. Deeler keeps the process democratic, which is the only way we can operate".

Danny Seim also has a side project began in the late 90's titled Lackthereof.