Deej is Derek John Kosbab. The family nickname of Deej arises from his initials DJ. Deej is an Australian artist known locally and worldwide for the artwork he has produced over the past 50 years.

Derek John Kosbab was born 5 November 1942 in Richmond, Surrey, England. Derek emigrated with his parents and brother Michael from post-war Britain in 1952. After a brief period living in Fingal Tasmania, the Kosbab family settled in Richmond, Victoria: from Richmond England to Richmond Australia.

Derek was taken out of school before he was fourteen years of age and after working for two years in a cigarette-wholesaler office he moved into an insurance office in Melbourne CBD. In 1962-3 he travelled around Australia working odd jobs. In 1964 Derek began employment as a teacher of dance in an Arthur Murray Dance Studio. He was to continue teaching adults to dance socially for more than 30 years: 20 years of which were in his own ABC International Dance Studio in Knox. During that time he graduated as a Fellow of the Federal Association of Teachers of Dancing (Australia and New Zealand) and a Member of the Imperial Society of Teachers of Dancing (London). At the same time he opened ABC Fancy Dress Hire that operated successfully for a decade before being sold.

It was during his time as the owner of ABC International Dance Studio that Derek realised that while he had successful businesses employing more than twenty people he lacked an education. After a year at Box Hill High School studying Year 12 English, Derek applied to Deakin University to be a mature-age, part-time, off-campus student. He was accepted and graduated Bachelor of Arts (Social Sciences) with Honours. Meanwhile, Derek had sold the dance studio and was working full-time in the not-for-profit sector delivering state and commonwealth funded employment and training programs for long-term unemployed adults. He enrolled for post-graduate studies and completed three Masters degrees and finally graduated with a PhD in Professional Education and Training.

In 2007 Dr Derek received the award Australian Adult Educator of the Year from Adult Learning Australia. Dr Derek John Kosbab worked at Victoria University for three years prior to retirement in 2013.