Battlegrounds has many interesting minions and I was wondering where they are coming from. I haven't played Wow or most of the single player stuff in HS so I don't know if these cards already made an appearance there. I'm talking about Goldrinn, Elistra etc. It would make for an interesting custom card competition too, to try to include them in the regular game.
Most BG cards are regular cards; Kangor is a HS only character, certainly. Elistra is probably as well, though not played for a bit. Foe reaper is a well known rare in WoW. Goldrinn, as mentioned, is a wild god. Garr/rag are MC bosses; Zapp, afaik, is HS OC. Murozond is head of the infinite dragonflight; Nomi is an exceptionally bad chef notable for burning stuff (though he got better as the expansion wore on, his legend was sealed quickly. Like how he charred food quickly.). Eliza, I think, is an OC, considering she's not related to Darkshire, and Bagurgle.. might be? Can't remember if the guy posing as a murloc in borean is called that. Nadina is a Belf in Wow; not a red dragon, from poking things. The beast is a UBRS boss, from the original dungeon. Bolvar is Bolvar, LK 2.0. Bigfernal is probably a pun on minfernal, a battle pet, which itself is a pun on infernal. Mythrax is a raid boss. Zerus seems to be HS only, though the art is certainly based on wow - Throne of the tides, the Vash'ir cata dungeon.
A lot of the BG onlies are generic minions, like acolyte of c'thun or similar.