picked him up the other day and was wondering who he was
Well, he's the Tzar of Kislev, the fantasy world's Russia.
Think he's the dad of the Tzarina, Katerina the Ice Queen.....maybe wife of....not sure
is he riding a polar bear? if so he's the king of kislev
He's the former Tzar of Kislev, the father of the current Tzarina Kattarin
thanks are the rules for him in the kislev white dwarf article and are they online
i would post the rules but i through mine away sorry

He is in the Kislev supplement that came free with one issue of White dwarf. Alas, rules dictate that I cannot post his rules online. Suffice to say that he is decent as far as an all Kislevite army goes. As to who he is, the others have explained, but as clarification: He is the tzar (leader) of Kislev (North of the Empire, South of the Chaos Watses). he rides a bed (can't recall the name) that he tamed and has a VERY special bond with, also bears are effectively sacred to Kislevites. Hope that helps!
The full book used to be online (on the UK GW site) as a pdf, that link shows only a few of the pages for some reason.
he rides a bed
does he last time i looked he didn't 
yea i have the model i was going to convert it to a dwarf bear rider now i don\'t have thank to reaper
Well, it was late and now ya know what i wanted Godbob

By late, I mean it was probably 10am by the point

I meant to put bear...