Who was the last honest president?

[Antonio the Sixth]

Depends what you mean by "honest". Clinton was a liar, but he didn't fool the electorate with fake campaign promises (well, he did far less than what he said it would, but we can't say he didn't try). Obama hasn't done anything that leads to think he's dishonest, even though like every politician he can't always say what he thinks.

The most outstandingly honest president was probably Carter.

[Antonio the Sixth]

Jerry Ford.  But come to think of it, I don't recall Dubya affirmatively lying about anything.  He just didn't turn in his homework assignments on a very regular basis is all.

His entire campaign (both of them) was a lie. And before someone says it's true for every politician... of course, to some extent, but few come close to his levels.