X2

X2 may refer to:

Mathematics

• Square (algebra), also known as the "algebraic square", a concept in algebra
• Chi-squared distribution, a theoretical probability distribution widely used in inferential statistics

Films

• X2 (film), a 2003 American sequel to the 2000 film X-Men (film). Also known as X-Men United.
• xXx: State of the Union, also known as X2 or XXX², a 2005 American film

Video games

• X2 (video game), a video game
• Final Fantasy X-2, a role-playing video game
• Mega Man X2, a platform game
• X2: The Threat, a space simulation game
• Dance Dance Revolution X2, an upcoming music video game for the PlayStation 2 by Konami
• X2, the main character in Star Wars Battlefront: Elite Squadron.

Transport

• Bell X-2, an experimental supersonic aircraft
• Sikorsky X2, a prototype, coaxial high-speed helicopter
• SpaceShipOne flight 17P, also known as "X2", the second Ansari X Prize flight
• Skycycle X-2, a rocket used by Evel Knievel
• HMS X2, a Royal Navy submarine
• Bathyscaphe Trieste II, also known as X-2, the US Navy bathyscaphe based on the Trieste
• SJ X2, used for the X2000 train system in Sweden
• Kawasaki X2, a personal water craft
• X-2 Dragonfly, the company designation of the Rotor-Craft XR-11 experimental helicopter of the late 1940s
• X-2 Rocket, the spacecraft used in Mission: SPACE in Epcot

Computer

• X2 (protocol), a pre-V.90 standard for 56k downstream modem communications
• Athlon 64 X2, the first dual-core desktop CPU manufactured by AMD
• A two-lane PCI Express slot
• A type of 10 Gigabit Ethernet optical transceiver
• Sony Ericsson XPERIA X2 smartphone

Other

• X2 (roller coaster), a Roller Coaster at Six Flags Magic Mountain
• Sendo X2, a Series 60 mobile phone
• The counterintelligence branch of the Office of Strategic Services, an American agency during World War II
• X-2, a hydrofoil owned by the Venture family on The Venture Bros.
• a keyboard synthesizer sold by Korg in the 1990s
• X2 is a transport interface used to connect eNode Bs together in a LTE/4G network.