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

[CSteefel]

Some very interesting posts.

Echoing some of the posts above, Sauron does seem a likely candidate in the 2nd Age, given that he deceived the men of Numenor so successfully, even if the fall of Numenor cannot be attributed to him alone. And perhaps more importantly, he did deceive the Elves of Eregion (with the exception of Galadriel). In the 3rd Age, I don't see much evidence that he deceived anybody.

Saruman was able to deceive the entire White Council, with the exception of Gandalf and Galadriel to some extent (it is stated that Galadriel preferred Gandalf as the choice for the head of the Council and that Gandalf did not share all he knew himself about the Ring that Bilbo had found, implying some level of mistrust). But even in the case of Galadriel, the suspicion was not strong enough that she was willing to derail Saruman's appointment. This is in contrast to Sauron, who was never capable of deceiving either Galadriel or Gil-galad, even in the 2nd Age. One might argue that Saruman initially was not evil, but the falsity of his intentions was clear from the time when he started to search the Gladden Fields secretly, as far back as 2851 as Raynor points out above. Add to that the deceit of the men of Rohan and you have a pretty good record.