Who, in The Lord of the Rings, was the most effective liar?

[littlemanpoet]

Originally Posted by Bêthberry

Ah, I see that a name is omitted from this list. Surely the most effective liar in Lord of the Rings is the author himself,

Clever, and your point is well taken; however, the question is asked of those "IN" LotR whereas the author stands outside it. So it is not, technically, an omission.

As for "too early", Raynor and others, it's an open debate as to what status the Appendices have by way of "IN LotR", as the question was stated. So I'll allow the appendices as part of LotR for the purposes of this discussion.

Effectiveness must take into account who gets misled and who doesn't. Wormtongue misleads the Rohirrim but not Gandalf. Saruman misleads Radagast & many of the Rohirrim but not Eomer and not Gandalf. And so on.