Union Jack is a trance music collaboration between Simon Berry and Claudio Giussani, a trance music producer from England. The duo has focused on acid and tech trance and has been closely associated with the Platipus record label, which was founded by Berry.

Disillusioned by the state of the early 1990s music industry, Berry and Giussani joined forces in 1993, firstly remixing Nicely’s "Away The Throttle Pedal Stop" before releasing their seminal first single, "Two Full Moons and A Trout". Their following single, "Cactus", reinforced their reputation before the release of their first album There Will Be No Armageddon. Enjoyable both at home and on the dance floor, it contained their third single, "Red Herring", which was a popular club song in the 1990s. The band was mentioned in the 1995 film, Hackers.