This is just a short quick version from American Progress, there are many more Cheney lies, some he has admitted himself.
Cheney declared 'with absolute certainty' that Iraq was developing nuclear weapons. On September 8, 2002, Vice President Cheney said, “We do know, with absolute certainty, that he is using his procurement system to acquire the equipment he needs in order to enrich uranium to build a nuclear weapon." At that time, however, the Department of Energy, the State Department and nuclear weapons experts “did not believe the aluminum tubes were for centrifuges to make nuclear weapons." After the invasion, months of inspections "found no evidence of hidden centrifuges or a revived nuclear weapons program."
Cheney said it was “pretty well confirmed” that Iraqi intelligence officers met with a 9/11 hijacker. The CIA has stated publicly that didn't have "any credible information" that the meeting took place. The bipartisan 9/11 Commission concluded the meeting did not occur. However, even after the 9/11 Commission issued its report, Cheney stood by his statements, saying in June 2004 that "we just don't know" whether the meeting took place.
Cheney said that Iraq trained al Qaeda terrorists. On December 2, 2002, Vice President Cheney claimed that Iraq had maintained long contacts with al Qaeda and “has provided training to al Qaeda terrorists.” This wasn’t true, and the administration knew it wasn’t true. The information came from a detainee known to be a fabricator months before the administration started using his claims as a basis for war. A February 2002 document by the Defense Intelligence Agency said that the detainee, Ibn al-Shaykh al-Libi, ''was intentionally misleading the debriefers.''