In its demo form, "Intruder" was centered around a drum machine pattern rather than live drums. He originally conceived the song as having a fuller arrangement at this stage of development.^[4] The working title for the song was "Marguerita", although Gabriel later changed it to "Intruder" once further elements were added.^[5]

The gated drum sound – which features heavily throughout the song – was achieved by Hugh Padgham and Phil Collins while working with an early SSL console at The Townhouse, which had noise gates and compressors built into every channel. The console had a reverse talkback feature that allowed the musicians to communicate with the producers in the control room. Pagham recalled that "one day, Phil was playing the drums and I had the reverse talkback on because he was speaking, and then he started playing the drums. The most unbelievable sound came out because of the heavy compressor."^[6]

Gabriel was excited by this development, saying that it would "revolutionise drum sounds", and subsequently built "Intruder" around the drums.^[7] He then instructed Collins to remove the cymbals from his kit and repeat the drum pattern throughout the entire song.^[4] During the song's run-through, Collins kept intuitively striking the air where his cymbals were previously situated, so Gabriel suggested that they place additional drums in those locations. The removal of these cymbals allowed Padgham to place microphones closer to Collins' drums.^[5]

At the request of Collins, Gabriel gave him a credit for coming up with the drum pattern.^[8] Gabriel contended that the gated-reverb sound had already been used on an XTC album, where the effect was used as more of "colouring agent". However, Gabriel wanted to utilize the gated-reverb drum sound to a greater extent than earlier uses of the effect by making it the focal point of "Intruder".^[4]

The drum pattern encompasses a one bar figure with six drum strikes: the third and sixth drum hits are played on a snare drum and the remaining drum hits occur on tom-tom drums. David Rhodes created the creaking noises heard during the intro and outro by scraping the lowest string of an acoustic guitar. A series of dissonant and percussive guitar and piano chords follow, which later segue into a descending melodic pattern accompanied by processed vocalizations.^[9] Melodically, Gabriel structured "Intruder" around flattened fifths on his piano to give the song "a sense of menace".^[10] The song's subject matter relates to a burglar breaking into a house and is told from the intruder's perspective.^[11]

• Peter Gabriel – piano, lead and backing vocals, whistling
• Phil Collins – drums, drum pattern
• Morris Pert – percussion
• Larry Fast – synthesizers
• David Rhodes – guitars, backing vocals

The song was often performed live by Gabriel in the early 1980s, and is included on his first live album, Plays Live (1983). It appears also on Gabriel's ninth studio album New Blood (2011) in symphonic version. Gabriel stated that the song's New Blood arrangement was inspired by the work of film director Alfred Hitchcock and composer Bernard Herrmann.^[12]

In 1992, the band Primus recorded a cover version of the song and included it as the opening track to their Miscellaneous Debris EP. The band later covered the song again in 2018 with Brann Dailor of Mastodon at a live performance in Sterling Heights, Michigan.^[13]