Dr Emma Levitt, of the University of Huddersfield, says the Tudor monarch commissioned portraits of himself on horseback and the frontline.
But in reality the only thing the notoriously randy king was worse at was being faithful to his poor wives.
To keep the illusion going, King Henry ordered a lavish life-sized statue be placed on his tomb, showing him on horseback in an “active knightly stance”.
But the monument - which would have cost the equivalent of £6million - was never built.
Dr Levitt said: “Henry was determined to construct a lasting image of chivalrous kingship and martial masculinity, even though his attainments in the military arena were rather slender.”
Her research into jousting scorecards from the 1500-1600s shows the king was actually terrible.
“It is indeed ironic that a king who lived in such opulence, who hosted such vastly expensive tournaments and pageants, whose court was known in its time as the most splendid in Europe, should lie in a plain vault, marked only by a marble slab.”
Last year a bombshell study revealed Meghan Markle’s distant relative was beheaded by Henry VIII.
The brunette beauty is an descendant of Lord Hussey, 1st Baron Hussey of Sleaford, inset, who fell out with the king.
He was a rich landowner who was accused of plotting a rebellion against the infamous Tudor monarch in 1536.
Lord Hussey was then thrown into the Tower of London after being found guilty of treason and was beheaded.
Ten generations down the family line was Thomas Markle, who fathered Meghan, 36, with Doria Ragland in 1981.