[1] Dean was very keen on natural history as a child, and Chinese landscape art and feng shui became particular influences on him during his time in Hong Kong.

[1] He was removed from a life drawing class by the principal for being "young and impressionable", and was informed he could not take it due to maths and physics being his other subjects, leading a switch to studying industrial design.

[2][7] He considered Rick Griffin's artwork for Aoxomoxoa (1969) by the Grateful Dead as his "first big visual shock" and bought the album prior to owning a record player.

[2] In 1968, during his third year at the Royal College, Dean was assigned a project which involved the design of a contemporary landscape seating area of the upstairs disco at Ronnie Scott's Jazz Club in Soho.

[3] Dean picked up work where he could, including covers for various jazz artists for Vertigo Records which he disliked, calling them "austere exercises" and too restrictive for the ideas he wished to convey.

[3] The experience led Dean to establish a commission before starting work he wanted to do, leading to a short period of financial hardship.

[9] By 1971, Dean's desire to produce artwork for rock bands had grown though he continued to pursue architecture and headed a small exhibition of his work in Florence.

The design is a result of a brief that Dean described as "credible African fairytale imagery" and features "flying elephants and not architecture", which became an early representation of the style he later achieved fame with.

[3] In mid-1971, during his search for work affiliated with rock bands, Dean sent a portfolio to numerous executives including Phil Carson, the European General Manager of Atlantic Records.

[10] The tour for Tales from Topographic Oceans (1973) featured a nationwide merchandising campaign including posters and t-shirts that led to the creation of the production company Brockum.

[11] While working on the art for Yessongs (1973), Dean and his printers Tinsley Robor secured a patent for "a way of going from gatefold to any number of pages, folded out of one piece of card".

[3] In the late 1970s, Dean had an idea for Living in the Third Millennium, a thirteen episode television show about the designs and technological challenges of the future, yet it never made it to production due to budget constraints.

The idea spawned from two ideas–Dean's earlier designs for a bedroom intended for the safety of children, and Martyn's "retreat pod" from 1970 that Stanley Kubrick borrowed for his film A Clockwork Orange (1971).

[13][14][7] In 2003, a project involving the construction of 264 villas, chalets, and apartments designed by Dean on a 65-acre site near Stourport-on-Severn, Worcestershire had entered the planning stage.

The project involved Dean and Kaluta producing an estimated 4,000 drawings for the game, including ideas for its animation, story, music, and motion capture.

[6] In 2013, Dean filed a $50 million lawsuit in the U.S. District Court in New York, alleging that director James Cameron had plagiarised 14 of his original images in the film Avatar (2009).

[21] In 2022, an exhibition of works by Dean and his daughter Freyja was displayed at the Haight Street Art Center in San Francisco, entited The Secret Path.

[11] Later in 2022, an immersive exhibition featuring Dean's artwork presented in high definition 4D audio and video with laser projections was held at the Gray Area Foundation for the Arts, also in San Francisco.

[11] Dean has two permanent galleries, his largest at Trading Boundaries, East Sussex in the UK and the other at The San Francisco Art Exchange.

[22] The rise of the compact disc in the 1980s led to what Dean described as a decline in combining music with art, with the jewel case looking "tacky" and a way for record companies sacrificing quality to save money.

[23] He cites the early CD reissue of Close to the Edge by Yes as one that particularly affected him as his inner sleeve artwork was missing, replaced with black and white text.