X1

X1 or X-1 may refer to:

Vehicles

• Bell X-1, the first aircraft to exceed the speed of sound in controlled level flight
• BMW X1, a BMW Compact Sports Activity Vehicle
• HM Submarine X1, a Royal Navy submarine
• Red Bull X1, the former name of the Red Bull X2010, a fictional car created for the game Gran Turismo 5
• SL X1, a former Swedish commuter train
• Sinclair X-1, an electrically assisted faired recumbent bicycle
• Wrightspeed X1, an electric sports car based on the Ariel Atom chassis
• X-1 Submarine, the United States Navy's only midget submarine
• Yamaha X-1 and X-1R, related Yamaha underbone motorcycles

Computing

• a one-lane PCI Express slot
• Cray X1, a supercomputer sold since 2003
• Electrologica X1, an early Dutch computer
• Sharp X1, a series of personal computers
• X1 Professional Client, an enterprise desktop search product made by X1 Technologies, Inc.
• X1 Technologies, Inc., a software company

Other

• X Minus One, an old time radio show
• x ⁻¹, the multiplicative inverse of x (another way to denote 1⁄x, one divided by x)
• Cygnus X-1 and Scorpius X-1, two astronomical x-ray sources
• M82 X-1, a candidate intermediate-mass black hole detected in January 2006
• Sony Ericsson XPERIA X1, a mobile phone
• First Eastern Counties route X1, a bus route from Lowestoft to Peterborough in Eastern England
• United States patent X1, by Samuel Hopkins (inventor)