1. Howland Reed
Youd be forgiven for not actually knowing who Howland Reed is, given that he is yet to actually appear in the narrative, being mentioned only occasionally in the third person by characters such as his children Jojen and Meera (travel companions of Bran Stark). Every mention that is made of him, however, indicates that he has an important part to play either in revelations or in future plot developments, even if nobody has any idea where he is at the present time. Having befriended the Starks (particularly Eddard and Lyanna) during a Tourney at Harrenhal, Howland fought in Roberts Rebellion, being the only person other than Ned to survive the battle at the Tower of Joy, where Rhaegar Targaryen had kept Lyanna (his seemingly mutual love) protected by three members of the Kingsguard. As a result of this, he is the only living person who is aware of the promise that the dying Lyanna extracted from Ned, which is widely believed to concern Jon Snow (said by many to be Rhaegar and Lyannas son). In addition to this, Robb Stark sent three individuals Jason Mallister, Maege Mormont and Galbart Glover to find Howland in Greywater Watch (the Reed family home) and deliver a declaration naming Robbs successor (which ties into the previously mentioned Jeyne is pregnant theory). Mallister has since been mentioned as having surrendered his home, Seagard, to the Freys, but no mention has been made of Galbart, Maege or their mission for some time. Given that GRRM isnt one to drop story arcs, no matter how minor they seem, this is certainly something to remember as we slowly edge closer to the releases of The Winds Of Winter and A Dream Of Spring.