I don't think Thenamir is anyone but Thenamir. He's just too much a one of a kind to be anything else.  
  However I have it on not so good authority 
 
  
 that Orlando Bloom is none other than our dear 
Barrow-Wight himself! What better way to hide from fangirls than to disguise oneself as a curmudgeonly moderator of such a well reputed forum as this?