X2 may refer to:

• X2, a 2003 movie also known as X-Men 2
• Bell X-2, an experimental supersonic aircraft
• Trieste II , the US Navy bathyscaphe based on the Trieste, and called X-2
• Final Fantasy X-2, a video game
• , another video game
• X2 (Chipset), the standard chipset for 56k downstream modem communications
• X2 train, used for X2000 train system in Sweden
• SpaceShipOne flight 17P, the second Ansari X Prize flight, which is also known as X2.
• xXx: State of the Union, or xXx 2 or X2

Additionally, X² may refer to:

• an algebraic square
• the Chi-square distribution in statistical analysis