Your best friend. His beautiful, shiny exterior is complemented by the drawing of a heart, symbolizing your love for him.
I invited your best friend Companion Cube, but he couldn't come, because you murdered him.

If Companion Cube should speak to you, don't acknowledge his suggestions.

The cake is a lie.
by Steven Willmy October 31, 2007
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The eminent center would like to remind you that the companion cube will not threaten to stab you and cannot speak. If you do hear the companion cube speak, ignore what it says as it would sooner destroy itself than be a burden to you.
I fucker the companion cube in the ass
by The Hater of haters December 4, 2014
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This Weighted Companion Cube will accompany you through the test chamber. Please take care of it.
by Frostblade October 16, 2007
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1.) A cube in the game Portal you are given to help you with tasks.
2.) Your best friend.
1.)This weighted companion cube will accompany you through the test chamber. Please take care of it.
2.) While it has been a faithful companion, your companion cube cannot accompany you through the rest of the test. If it could talk - and the Enrichment Center takes this opportunity to remind you that it cannot - it would tell you to go on without it because it would rather die in a fire than become a burden to you.
by joe matt October 24, 2007
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The most beloved "character" in the Valve game Portal, it is considered a character in most tenses of the word due to its helpfulness and aura of friendliness, though it does not talk, and thus cannot threaten to stab you.

The Companion Cube is only used in one level of the game, but it leaves a lasting memory and somewhat of a motive for the main character to "kill" GLaDOS, the antagonist of the game.

The main character, however, does not seem to have as much of a link or heart felt connection as does most other test subjects of the Apeture Science Computer-Aided Enrichment Center. This is shown by graphetti drawings on the walls in a hidden room within the level of the Companion Cube. At the end of the level, the main character is forced to euthanize the Companion Cube in a pit of fiery liquid metal. After which GLaDOS congratulates the main character and comments that she is the quickest of all test subjects to euthanize the Companion Cube.

At the end of Portal, the main character finally receives the cake in a brief party in which the Companion Cube is invited and surprisingly shows up.

The Companion Cube is your very best friend in the world, is male, cannot talk (though in the event that it does, Apeture Science strongly disregards listening to any of his suggestions), and is covered in hearts.
The Weighted Companion Cube would never hurt me.

Why? Why? Why? Why? Why?
by Xivili October 26, 2009
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A special version of the Aperture Science Weighted Storage Cube. This cube is integral to your success.
Your Aperture Science Weighted Companion Cube will never threaten to stab you, and in fact cannot speak. If your Weighted Companion Cube does speak, please disregard its advice.
by GLaDOS October 21, 2007
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Your very best friend. It will not hurt you or talk to you, or even stab you. However, euthanization is eventually required.

It is a cube with hearts on the sides given to you in the valve game portal. You use the cube in only one level and it is shortly thereafter incinerated, yet its small appearance has gathered a cult like basis.
I hit your mom last night, like she was the Weighted Companion Cube.

The cake is a lie, unlike the Weighted Companion Cube.
by J J Bakes November 19, 2007
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