The denial of the holocaust of 6 million Jews by Nazi Germany is a common theme of racist propaganda usually by anti-semitic and/or fascistic groups who try to minimise the suffering of the Jewish people or to demonise the state of Israel. The facts of the holocaust are well understood and accepted by the vast majority of academics and historians. There is legitimate historical debate around the causes and details of the murder of European Jews, homosexuals, gypsies, communists and other minorities but denialists frequently focus on Jews alone.
Publishing tracts in favour of or promoting denialism is illegal in some European countries and Israel, but is actively encouraged and sponsored in Iran and Syria - who see Israel as their enemy. No such restrictions are found in the UK and USA under free-speech grounds but the term 'Denialist' is refuted by proponents who may promote such views under the guise of 'Revisionism'. However, where revisionist historians may legitimately dispute the interpretation and impact certain historical events have had, a denialist ignores salient facts and ignores or minimises not just the interpretation but the facts themselves.
Historian David Irving published several books on German history, some well received by peers but others denying or minimising the holocaust, and was referred to as a 'Denialist' by US author Deborah Lipstadt in her book "Denying the Holocaust". She accused him of "bending evidence...until it conforms with his ideological leanings". Irving sued her for libel and lost.