Technicolor Death

So the Final Battle is finally over. The Big Bad, a powerful personification from hell and/or an homicidal robot from the future, has been struck a lethal blow and is now done for. How does Hollywood celebrate this climactic moment? Easy, by having the defeated foe then die in a spectacular fashion, with lots of special effects and unusual things happening to him, such as explosions, flashes, gradual disintegration, things melting, etc.

Note that this is not just dying in a flashy way, this is when the flashiness comes from the death itself, so for instance a character dying by having a bomb inside him is not this trope, as the explosion comes from the bomb and not from the character's death.

Quite common in video games, especially for bosses—a good death scene is part of the reward for bringing down such an imposing enemy, and frequently Stuff Blowing Up makes for a good death scene.

See also Critical Existence Failure for when death is always a sudden thing, Ludicrous Gibs for gory existence failures. In Video Games, it can become a justification for Everything Fades for Mooks. A supertrope of Disappears Into Light.

As a Death Trope, Spoilers ahead may be unmarked. Beware.

Examples of Technicolor Death include:

Anime and Manga

The Anti-Spiral King in Tengen Toppa Gurren Lagann probably takes the cake, dying in seven sequential multicolored galaxy-spanning explosions.
In the 3rd Sailor Moon movie (the Super S one), the main villain dies in this manner, where it shows her already blob-like face melting and swirling (she's merged with a "black hole" at this point so she looks like a glowing ball with a face on it) and then the whole thing explodes.
The Angels of Neon Genesis Evangelion virtually all do this, often with technicolor crosses of light.
Lampshaded in Mirai Nikki by Yuno's reaction to the death of The 3rd.

"Tch, That's it?" *stretches*

Comic Books

At the climax of War of the Green Lanterns, all the colors of the rainbow shoot from Krona as Hal kills him.

Film

The Wizard of Oz: "I'M MELTING!! I'M MELTING!! OH WHAT A WORLD!! WHAT A WORLD!!"
The explosive death/destruction of Agent Smith in The Matrix and all of the Agent Smiths (Agents Smith?) in The Matrix Revolutions.
Highlander. The Quickening that occurs when an Immortal dies.
The Lord of the Rings (movie version). Although it's right in the prologue rather than the end of the movie, death for Sauron basically means becoming the exploding man.
- And of course there's the more understated, but no less satisfying, implosion of The Witch-King near the end of Return of the King.
The T-1000's death in Terminator 2 is a notable example of a Shapeshifter Swan Song, but it becomes even more spectacular when the T-1000 starts to do things like split into two heads, form into a mouth, and invert that mouth as it tries to save itself.
It's not enough for sunlight to just kill Gremlins. It has to melt them alive.
The Nightmare King from Little Nemo: Adventures in Slumberland had a very colorful death.
The Emperor's death in Return of the Jedi was like this.
War of the Colossal Beast is a literal example. The entire film was shot in black and white EXCEPT for the title character's climactic death.

Literature

In The Wonderful Wizard of Oz the Wicked Witch of the West melts after being thrown a bucket of water, her weakness.
In the Star Wars Expanded Universe, the Emperor's explosion upon death in Return of the Jedi is applied to a lot of dark Jedi, such as Joruus C'Baoth in The Thrawn Trilogy.

Live-Action TV

When Power Rangers villains die, they go out with a bang. Sometimes it's such that you'd think the monster's destruction would do more to the city than the monster would have if left alone. Mighty Morphin Power Rangers in particular went the distance, with all sorts of flashy and colorful effects as the monster staggered around, leading up to the final kaboom (which could consist of two or three explosions.) They haven't looked like that in a while, even for main villains.
The Beast in Angel season 4 dies this way, with sunlight exploding out of him after Angelus punctures his rocky hide.
Halfrek's fiery death in the Buffy episode "Selfless" is like this, too.
Many regeneration scenes in Doctor Who are like this, with the obvious difference that the character in question is in a sense dying but simultaneously getting better. They're also unusual in that it's the death of the hero, not the villain. No two regenerations have been shown to be quite alike; mostly it's been a case of how the special effects team wanted to show off at the time.
- David Tennant into Matt Smith looked pretty much like Christopher Eccleston into David Tennant... but Tennant-into-Smith caused explosions throughout the TARDIS interior and caused it to crash. Just why this is is the subject of much Fan Wank, but the real answer is "the production team wanted to make some tweaks to the ship."
Kamen Rider generally uses explosions for its monster deaths, like Power Rangers, above. Some, however, decide to get fancy, such as the "burst into blue flames, then collapse into dust while a Greek letter hovers over your body" effects from Kamen Rider Faiz.
When demons die in Supernatural they explode with red flashing lights. Angels take this to the next level where not only does white light explode from their body, but covers the entire room of wherever they're at.

Video Games

All Final Bosses from Final Fantasy I through X slowly disintegrate, as well as Final Fantasy Tactics. Sometimes with flashing.
- In Final Fantasy X this is integrated into the plot: Monsters are formed by unsent souls, when they're killed these firefly-like souls emanate from their remains.
  - Even then, you get some pretty cool death animations. A notable one that comes to mind is the jellyfish Sinspawn on the trip from Besaid to Kilika. It shudders, gets compressed into an oily black sphere, then explodes into a cloud of fireflies.
    - The most over-the-top and spectacular example in the series yet has to be Ultimecia's final defeat. First she shudders, then her body releases explosions, then she fires a large laser into the sky from her (lack of a) face and then countless beams of light erupt out of her body until almost the entire screen has gone white. THEN she explodes. And it's still not over, since Ultimecia's distorting body then gets a slightly disturbing close up in negative colors and proceeds to disintegrate in a shower of bright light. AND SHE SURVIVES IT.
      - Challenging that is the needlessly over-the-top and long death animation of Yu Yevon. Imagine the Ultimecia example above, but with sheer out-and-out disintigration coming from such a small target. It needs to be seen to be believed.
- Final Fantasy XII has a flying cybernetic Clock Punk engine of destruction as its final boss, created when the Big Bad's apotheosis causes him to spontaneously accumulate debris and machinery from his own battle fortress. In short, not only does he get a Technicolor Death, he also gets a Technicolor Transformation Sequence.
Though the Final Boss doesn't do this, all the bosses (and standard enemies) in Twilight Princess explode upon dying into little Twilight fragments.
- All bosses except the final one in Legend of Zelda: Phantom Hourglass turn into gold, disintigrated partially, explode into a column of sand, and then the sand freezes in midair.
- And of course, in Wind Waker, with standard enemies dissapearing into puffs of smoke.
The first Wild ARMs has each generic enemy dying by flashing colors and collapsing vertically into a little pool on the ground. Bosses get the more enhanced effect of flashing colors while beams of light shoot around and a big flash (if I remember correctly)
- Most of the bosses in the remake flash shake, and disintigrate, piece-by-piece.
Defeated bosses in the Mega Man Zero series are usually engulfed in a spherical blast that emits beams of light after being defeated. The explosion may be Justified due to them being robots; since Zero's trademark weapon is a sword, it may have compromised their power systems. The radiating beams of light part? Not so much. Also, the attack that depletes their health meter causes much more damage than any other attack (blowing a chunk out of them if it's a charged beam shot, Diagonal Cut if it's with the sword), but that's probably another trope.
- Mega Man and the bosses he fights turn into 8 lights and explode in 8 directions when killed.
- Mega Man X bosses recoil in pain and explode for about 10 seconds as the background fades to white and they disappear into the background.
Slain bosses in The World Ends With You fulfill this in two different ways, first turning black on a background of white noise, then radiating beams of light, and finally vanishing in a white burst.
In the old ZX Spectrum game Chaos, when a wizard is killed his sprite explodes across the board in all eight directions and all eight colours. And it is awesome.
Bosses in the Mario & Luigi RPGs tend to explode into glowing stars and lights when they die.
The bosses in the old Sega Genesis game Decap Attack would flash on and off brightly like a strobe light for several seconds as small explosions engulf them before disappearing.
Ansem really, Xehanort's Heartless from Kingdom Hearts died in a very awesome, spectacular explosion- subverted in that he's, strangely, fine in the next cutscene. ("fine" in the sense that he's still alive) Then, he dies again, in a shower of light beams... although it is unclear if all of those beams came from Kingdom Hearts, or if some of them were actually caused by his death, as this trope demands.
- Marluxia from Chain of Memories had an epic disintegration into Cherry Blossoms and swirly darkness amidst a background that resembles a darkened sky
Each of the Cobras (the team of renegade commandos) in Metal Gear Solid 3 explode after being killed. This is played for laughs in some of the Secret Theater scenes.
Monsters in Okami tend to dissolve into flowers. Boss monsters can be more spectacular; for instance, the Spider Queen turns into a giant lotus flower in the cutscene following her death. Devil Gates also cause the landscape to bloom when they're destroyed.
The way SHODAN "died" in System Shock 2.
The way bosses died in Darius Gaiden and G-Darius- streaks of light pour out of them, then BOOM. Subverted by earlier games in the series, the bosses would just turn grey and drop off the bottom of the screen.
In most of the games developed by Treasure (Dynamite Headdy, Gunstar Heroes, Mischief Makers, what have you), the bosses and even minibosses tend to explode in incredibly over-the-top ways, whether or not they're robots or have any mechanical components which could logically detonate. Most of these explosions are done with only one explosion sprite that's used like a particle effect, especially in their earlier games.
In Minecraft, normaly while mobs simply fall over and vanish in a puff of smoke when killed, the Enderdragon starts to explode and disintergrate pixel by pixel while shooting out beams of light.
GLaDOS' death in Portal causes her chamber to explode/implode, blasting everything in there (including Chell) outside.
Bosses in the original Yoshi's Island would go out with multiple brightly colored, sparkly explosions.
The Final Boss of EarthBound dissipates into static upon death and simulates the TV turning off.
Kid Icarus: Uprising has Medusa disintegrating into nothing from head to toe after freezing in place, and Hades also disintegrating as the beam from the Final Strike pummels him.