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

[Aganzir]

Originally Posted by Alfirin

whereas lying to the morgul king if the lie was found out risked incurring the wrath of both the Morgul king (who is proably more powerful that Saruman one on one already by the time of the lie) and of Sauron himself. Even if Saruman was not yet in Sauron's thrall lying to the morgul king would be a risky move at best.

Why might the Morgul king have been more powerful than Saruman? He was nothing but a Man, a wraith, even though one of Sauron's most powerful captains, whereas Saruman was one of the Istari and of much greater origin than the Morgul king. Sauron had far greater armies than Saruman though, but what could he have done to Saruman himself? And it would have been only ridiculous, had Sauron started to fight against Saruman instead of Gondor and Rohan...

I voted for Saruman.

I fail to see what made Boromir a liar. He never meant anything bad to happen, it wasn't his fault the Ring attracted him, and he never really lied. I would forget the incident on Amon Hen- Boromir wasn't being himself and soon recovered and regretted what he had done. And, as far as I see it, Boromir's lies didn't cause anything bad to happen, on the contrary. Frodo succeeded because he left the Fellowship then, and we don't know what would have happened, had he not done it on that very moment.
Sauron was scarier and more powerful as a servant of Melko than as the Dark Lord on the throne of Mordor. Furhermore, his power was rather in violence than in verbal things.
Gollum never really achieved anything by lying. In the end all his lies turned against him. The same goes with Denethor.

Even though he never had as great plans and motives, I think Wormtongue was in a way a better liar than Saruman- mainly because he wasn't too full of himself to see what happened around him (which happened to Saruman). What makes Saruman more effective is that he really used his power and knowledge. Wormtongue had a strong influence on Rohan's politics, true, but why was he working? Not for his own fun, surely, he never gained anything by betraying Théoden. He was Saruman's puppet, and his lies came directly from Saruman.

Saruman dared to cheat the other members of the White Council for quite a long time, and I think that was riskier than lying to the Morgul king. And would he have been revealed even that early, had he not decided to tell Gandalf about his plans?

Saruman's voice was of course an effective talent when it comes to lying. Nogrod said Saruman's lies were not profound enough, but it was his voice that made them profound and believable if they weren't that by themselves.

If there was something Saruman succeeded in, it was destroying the Shire for a while. After Saruman's death the damage done was fixed, but the whole country was under his control before Frodo & co. returned.
Everyone can decide themselves if it was a difficult thing to scare some Hobbits who didn't know anything about the cruel world, though...

Considering the Downfall of Númenor, I think Saruman would have managed to destroy Númenor with the same means Sauron did, had he been there in Sauron's stead.