Historical Downgrade

Sometimes a historical figure is twisted from their original roots into something more grand or more vile, as a Historical Hero Upgrade or Historical Villain Upgrade.

But sometimes a story isn't interested in either of these with a figure. It neither wants him to be lionized or necessarily vilified, but at the same time it can't resist taking some of the shine off of them. While this could easily be just an attempt to humanize these figures and try to be more historically accurate, it's often far too easy to go that extra step and stuff a bit of Straw Loser in there. The result is a Historical Downgrade: while either a heroic or villainous shift could be said to be an increase in status, this take is definitely a lessening of stature no matter where the figure started out.

Those who have been lauded by history are most often made the target of this, but those who got the short end of the stick aren't immune... especially when their villainous portrayal is more pathetic than intimidating.

Examples of Historical Downgrade include:

Film

The 2010 Robin Hood movie was quite fond of this, the most obvious example being King Richard, who wobbles around the battlefield drunk and winds up being killed by a French cook taking a potshot. Prince (and then King) John meanders between this and the villainous version. The Sheriff definitely gets this, being rendered so laughably incompetent that even if he had been given a chance for villainy, he probably couldn't have managed it.
- Going back earlier, Prince John got this in Disney's animated version of Robin Hood... he's so childlike and sad that he can't properly be called a villain, he's just somebody for kids to laugh at.
Time Bandits did this to every historical figure they met, except for King Agamemnon. Although still a hero and all around nice guy, King Agamemnon still would have lost his battle against the minotaur without Kevin dropping in on the battle.

Literature

The Masters of Rome series of novels does this to Brutus, who is portrayed as a basically decent person (at least compared to most of the other characters), but with the flaws of greed, timidity, pedantry and cowardice.

Live Action TV

Blackadder thrives on this trope. Case in point, the second Blackadder series portrays Queen Elizabeth I as a total nutjob. Prince George (aka Prince Minibrain) of the third series would also count. Prince George may have been a glutton and profligate spender, but there's no indication he was dumb.

Western Animation

Robot Chicken does this to Adolf Hitler.
Time Squad played with this. The usual mission of the eponymous squad was to correct an individual who had, by the cause of whatever temporal anomaly, been on the receiving end of a Historical Downgrade, and it was their job to fix them and save history.