Phalanx

The head & torso was a prototypical sentrybot, but it had four legs, ending in thick spheres, like enormous ball barings that someone had covered in tire treads.  The four legs were thicker than what one would expect for a sentrybot, which only added to the sense of dread one might have when spotting it. It had a square bulky flashlight over its right shoulder on a swivel mount, which looked like it had once been a semi-truck headlight – it was – and two very human looking arms and hands. On its back clamped in place with magnetic and steel reinforced clamps was some kind of armored container, with a Mr. Handy engine built into it for stability.

“Stand and be counted. Explain your purpose for being here.”

The voice was surprisingly human like, and female, and not at all what one would expect from a sentrybot (Adrienne Barbeau    as Selina Kyle from Batman the animated series).