Agave bracteosa

That exposure is actually southern and western, and gets lots of sun, but it's just inside for the picture. I just got it today, so it may not have been in the best light previously. It will spend all its life either outside in full, unobstructed, blazing, southern exposure and then be overwintered in my south-facing garage. Thanks for the ID.

The plant is so etiolated, it is difficult to ID, but best guess is A. weberi, which does not bode well for its future in a container (any container), considering it grows to 12' across.