We all love a thrilling and creative video game boss fight, and one of the most common conventions of a boss battle is to have them transform in some manner, either before or during the battle.
Typically these transformations tend to be relatively modest so the character remains somewhat recognisable, but sometimes they're mutated beyond any and all recognition in a way that catches the player completely off-guard.
From distinctly humanoid characters turning into grotesque blobs, to bosses who ended up multiplying their mass and scale hundreds or even thousands of times over, these bosses all changed things up in a totally insane way that nobody saw coming.
It doesn't mean they all went down well with fans, though: some of these ridiculous transformations admittedly felt out of place or unintentionally hilarious, but many at least offered up an awe-inspiring change of pace, style, and tone that players won't ever forget.
If nothing else, these boss fights are all proof perfect that you can never be 100% sure where an encounter is going, and what the developers might have waiting up their sleeves to bamboozle you with...
10. Guardian Ape - Sekiro: Shadows Die Twice
Let's kick things off with a recent yet all-timer boss transformation that left players both respecting the ingenuity on display and loathing how utterly cunning a ruse it was.
Like most enemies in FromSoftware games, Sekiro's Guardian Ape will make short work of you if you don't show it the proper respect, but even if you last long enough to deliver an apparent coup de grâce, the fight still isn't over.
That's right. You'll think the Guardian Ape's goose is cooked once you've used a Shinobi Execution to decapitate it - because why the hell wouldn't you? - but around 15 seconds later, it'll clamber back to its feet and resume the fight, all while carrying its severed head around in one hand.
And to rub salt in the wound, it'll also pick up the sword you used to decapitate it - which was previously jammed in its neck - for a considerably hairier second phase.
This was a fantastic subversion of expectations, by assuring players that they need to remain on their toes even after depleting a boss' life bar.