X2, a 2003 American movie also known as X-Men United

Skycycle X-2, a rocket used by Evel Knievel

A two-lane PCI Express slot

Chi-square distribution, a theoretical probability distribution widely used in inferential statistics

Athlon 64 X2, the first dual-core desktop CPU manufactured by AMD

Bell X-2, an experimental supersonic aircraft

SpaceShipOne flight 17P, also known as "X2", the second Ansari X Prize flight

XXX: State of the Union, also known as X2 or XXX², a 2005 American film

X2 (PWC), a personal water craft

Sikorsky X2, a prototype, coaxial high-speed helicopter

Square (algebra), also known as the "algebraic square", a concept in algebra

Bathyscaphe Trieste II, also known as X-2, the US Navy bathyscaphe based on the Trieste

X2 train, used for X2000 train system in Sweden

X2, a video game

HM Submarine X2, a Royal Navy submarine.

Final Fantasy X-2, an RPG video game

Megaman X2, a platform game

X²: The Threat, a space simulation game

X2 (protocol), a pre-V.90 standard for 56k downstream modem communications

X² (roller coaster), a Roller Coaster at Six Flags Magic Mountain

The counterintelligence branch of the Office of Strategic Services, an American agency during World War II

X-2 is the name of the fictional space shuttle series in the Epcot attration, Mission: Space

X-2 is the name of the Hydrofoil owned by the Venture family on the Venture Bros.