NPC: Serpentshrine Lurker
ID: 21863

Sources show he should be bannishable, unless it is a pre-nerf thing where he should not be.

http://wow.allakhazam.com/wiki/trash_mobs_(ssc) (2008-06-15)
http://wow.gamepedia.com/index.php?title=Serpentshrine_Lurker&oldid=881420 (2007-09-16)
http://www.wowhead.com/npc=21863/serpentshrine-lurker#comments:id=130308 (on 2007-08-01 Patch 2.1.3)