He was born in the city of Leicester in the English Midlands, into what he calls a "working class" family. Having wanted to be a professional footballer for quite some time, he left school to play for Coventry City and Hereford United in the English league, where he played as a goalkeeper.
After leaving the BBC he became an activist for the Green Party rising swiftly to become their media spokesperson. He left the Green party in 1991 and began to express unconventional views. He began to wear only turquoise and in different interviews claimed that he was God or the son of God. In an infamous interview on the Terry Wogan show in 1991 his announcement that he was "a son of the Godhead" and that Britain would be devastated by tidal waves and earthquakes was met with laughter from the studio audience, derision in the press and suggestions that he was mentally ill. In a more general sense, although his supporters note that he described all humans as 'children of God' or of some sort of god, and that the confusion resulted from his scrambling to explain his spiritual 'apotheosis'. After being widely derided and ridiculed, he disappeared from public view for a short time.
He returned to the limelight in the late 1990s with a book, The Biggest Secret: The Book That Will Change the World. In it he claimed to have discovered that the world was being run by a New World Order, controlled by a race of reptilian humanoids or reptiloid aliens or some such interdimensional race (he wavers on what exactly they are, only giving possible explanations). The group, known as the Babylonian Brotherhood, implicates practically every world leader as either a reptilian, or working for them (he suggests that they are slave-like victims of multiple personality disorder). The evidence for this is often considered absurd by non-adherents. For instance, he apparently claims that the car-rental company Avis is actually a front for the Brotherhood. His evidence? Avis spelled backwards is Siva, a member of the Hindu pantheon. However, his supporters tend to concentrate on the volume of more believable evidence he presents, such as the recurrence of the reptilian archetype in myths worldwide. For example, the Ancient Sumerians worshipped apparently reptilian gods called the Anunnaki, and the Ancient Maya of Mexico claim that all their knowledge of the heavens came from their god of wisdom and astrology, Kukulcan, sometimes depicted in Maya art as a reptilian humanoid with a crest of feathers on his head (this god later became the Aztec god, the Plumed Serpent, Quetzalcoatl).
Some anti-racist activists around the Western World have decried Icke's theories as being anti-semitic, saying that when he speaks of reptiles he is speaking of Jews. However, Icke has denied those allegations. He maintains that the reptilians are not humans of any race, but are extra-dimentional entities that enter and control human minds. He also says that what he calls the "white race" (those with blue eyes in particular) are most susceptible to reptilian influence.
He has since published a number of additional books following this theme at various levels of detail, the first being too large to be read by most casual readers. His latest work continues in this thread, an attempt to explain the September 11, 2001 Terrorist Attacks as being a part of this reptile-led conspiracy.