X-1 may refer to:

Transportation

Aircraft

Bell X-1 The Bell X-1 (Bell Model 44) is a rocket engine–powered aircraft, designated originally as the XS-1, and was a joint National Advisory Committee for Aeronautics– U.S. Army Air Forces– U.S. Air Force supersonic research project built by B ...

, the first aircraft to exceed the speed of sound in controlled level flight

Automobiles

Lada X-1 The Lada X-1 was a concept car designed by Lada in 1981. It can be seen as the forerunner of modern MPVs. The shape was very aerodynamic and like the later Fiat Multipla it also had the headlights up by the windscreen. The length of the car was 4 ...

, a 1981 Soviet concept MPV * McLaren X-1, a 2012 British one-off sports car based on the 12C

Cycles

* Sinclair X-1, an electrically assisted faired recumbent bicycle * Yamaha X-1, a commuter-style motorbike

Watercraft

* X-1 Submarine, the United States Navy's only midget submarine

Technology

Xbox One The Xbox One is a home video game console developed by Microsoft. Announced in May 2013, it is the successor to Xbox 360 and the third console in the Xbox#Consoles, Xbox series. It was first released in North America, parts of Europe, Austra ...

, a video game console * a one-lane

PCI Express PCI Express (Peripheral Component Interconnect Express), officially abbreviated as PCIe, is a high-speed standard used to connect hardware components inside computers. It is designed to replace older expansion bus standards such as Peripher ...

slot

Arts, entertainment, and media

X Minus One ''X Minus One'' is an American half-hour science fiction radio drama series that was broadcast from April 24, 1955, to January 9, 1958, in various timeslots on NBC. Known for high production values in adapting stories from the leading American ...

, a 1950s American radio show * ''X-Men'' (film), the first film in the ''X-Men'' franchise *

X-One ''XONE'' (formerly ''X360'') was a monthly magazine produced by Imagine Publishing in the United Kingdom. XONE was the UK's #1 selling independent dedicated Xbox 360 and Xbox One magazine, covering news, previews and reviews. The magazine's commu ...

, monthly magazine produced by Imagine Publishing

Other

* ''x''⁻¹, the

multiplicative inverse In mathematics, a multiplicative inverse or reciprocal for a number ''x'', denoted by 1/''x'' or ''x''−1, is a number which when Multiplication, multiplied by ''x'' yields the multiplicative identity, 1. The multiplicative inverse of a ra ...

of ''x'' (another way to denote ''1⁄x'', one divided by ''x'') *

Cygnus X-1 Cygnus X-1 (abbreviated Cyg X-1) is a galactic X-ray source in the constellation Cygnus and was the first such source widely accepted to be a black hole. It was discovered in 1964 during a rocket flight and is one of the ...

and Scorpius X-1, two astronomical x-ray sources *

M82 X-1 M82 X-1 is an ultra-luminous X-ray source located in the galaxy M82. It is a candidate intermediate-mass black hole, with the exact mass estimate varying from around 100 to 1000 solar masses. One of the most luminous ULXs ever known, its luminos ...

, a candidate intermediate-mass black hole detected in January 2006