Bold-faced liar - Idioms by The Free Dictionary
One who tells blatantly obvious and/or impudent untruths easily and with little or no attempt to disguise the lie. Everyone knows he is just a bold-faced liar. It's a wonder anyone believes a thing he says anymore.
References in periodicals archive
I do remember Clinton wagging his finger at the American public and saying, "I did not have sex with that woman - Miss Lewinski." I know a bold-faced liar
when I see one.