Tesseract

Hence the cube determined by these axes is the face of the tesseract which we now have before us.

[…]then it would trace out a higher cube, or tesseract, and each of the six surrounding cubes, carried on in the same motion, would trace tesseracts also,[…].

"I shall just sit down for a moment and pop on my boots and then I'll be on my way. Speaking of ways, pet, by the way, there is such a thing as a tesseract."

When the Tesseract's energy levels spiked, Selvig proved unable to stop it and Loki arrived on Earth via a Tesseract-created portal.

Cooper sees his younger self due to the tesseract in Interstellar.