A Sisters of Silence Kharon Pattern Acquisitor at Warhammer World.
Built to approach its targets silently and with utmost stealth, the Kharon Pattern Acquisitor is deliberately made to be a thing of mystery and terror when its presence is unveiled. Used primarily in a paramilitary role by the Sisters of Silence, it can suppress civilian resistance with lethal effect, its hellion cannon cutting through rampaging mobs and destroying makeshift barricades. Against greater threats, various payloads of missiles can be deployed, including sophisticated antipsyker warheads.
I always have thought as this as one of the pure SF models that you can get for the Imperium. Something which is more than tracks and armour of the Space Marine vehicles. It is a rather creepy model and a menacing addition to any tabletop.