Weighted Companion Cube
Aperture Science door
Aperture Science Weighted Companion Cube
Alternate names Companion Cube
Appearances Portal, Portal 2
Race Weighted Storage Cube
Roles Weighted Storage Cube
The Enrichment Center reminds you that the Weighted Companion Cube will never threaten to stab you and, in fact, cannot speak.
— GLaDOS • Portal

The Aperture Science Weighted Companion Cube, or simply simple the Companion Cube, is a Weighted Storage Cube that appears in Portal and Portal 2. It is first introduced in Test Chamber #17 and is used as a means of getting around (using as stairs), defense (blocking the High Energy Pellet), and weighing down buttons.

At the beginning of the chamber, GLaDOS repeatedly emphasizes the fact that the cube is non-sentient with the apparent intention of creating an emotional bond between the Testing Subject and the cube. At the end of the testing track, she makes the subject incinerate it.

In Portal 2, the cube is used in one of the chambers. If you decide to take it to the chamberlock, GLaDOS will fizzle it and state that they are sentient. ("I think that one was about to say 'I love you.' They ARE sentient, of course.")

At the end of the game, she decides to give Chell's original Companion Cube back.