Ragnarok (tank)
The Ragnarok heavy tank was first made during the Krieg civil war, as an alternative to the Leman Russ. A knock-off of the Soviet KV-2 with the usual 40K additions of an even bigger gun and no space for ammunition or an engine (a little unnecessary, as the KV-2 was already pretty ridiculous, being built around a gun designed to one-shot bunkers), Firaeveus Carron would have a fit if he ever saw one. Used by those crazies the Imperium calls the Death Korps of Krieg, siege platoons or any regiment too poor/under-equipped to get their hands on a Leman Russ, this thing is slow, heavy, armoured like hell and capable of dishing out the same punishment as a Leman Russ. Performing surprisingly well for a Kitbash, the techpriests on Lucius decided to tidy it up, dub it the "Mobile Bunker Mk 1" and then start churning them out. This is actually good when used as an infantry tank, like the pre-Heresy Malcador was a good cavalry tank. Look up on some other wiki what those types of tanks are, if you're curious.
For those that want a Ragnarok but don't want to kitbash it, Maxmini actually has a full kit for one here called the Gothic KV2 Tank. Makes you wonder why Forge World, with the boner they had for the Death Corps, never made one themselves.