David Myatt
David Wulstan Myatt (born 1950), formerly known as Abdul-Aziz ibn Myatt and Abdul al-Qari, is a British author, poet and philosopher, a former National Socialist, later for a period a Muslim, later supporting a philosophy called "The Numinous Way".
Wikipedia describes allegations of former associations with occultism, Combat 18, and Al-Qaeda and with crimes committed by others, as well as stating that since 2010, Myatt has written extensively about his rejection of his extremist past and about his rejection of extremism in general.
Wikipedia also states that "Myatt is regarded as an "example of the axis between right-wing extremists and Islamists"", despite that such dramatic changing of views are very rare. See also Horseshoe theory and True Believer.