Dennis, who in later life become a successful poet, was diagnosed with cancer in 2012. He passed away from the disease at his home in Warwickshire yesterday.
In 1974 he founded Dennis Publishing, publisher of Men’s Fitness, Auto Express, Bizarre and PC Pro, but in recent years is best known for producing The Week, one of the highest-circulating current affairs titles in the UK.
Kevin Costello, the chief executive of Haymarket Media Group, said: "I am deeply saddened to learn of the loss of Felix Dennis. A close friend of Haymarket, Felix was a charismatic, inspirational man and a publishing legend. My thoughts are with his family, friends and colleagues at Dennis Publishing."
A statement from Felix Dennis' office said: "Felix was a publishing legend, famed for his maverick and entrepreneurial style and, more lately, a successful and much loved poet. He will be greatly missed."
Dennis was passionate about forestry, and created The Heart of England Forest, a charity that is working to create a large forest of British trees in Warwickshire. Below are some of the initial condolences expressed via Twitter.