Bowser now (top) and then (bottom)
Bowser has played many roles over the years. We know him best as an interloper in the Mushroom Kingdom, but the King of all Koopas has also dabbled in shoot fighting and is well known as a bad boy kart racer. We've even witnessed his Fauntleroy-esque tantrums, in Yoshi's Island. Still, it was the original Super Mario Bros in which Bowser showed himself to be the archetype of the video game boss. His influence over later video game tyrants can be seen primarily in his interior decorating decisions, as every subsequent boss also decided it would be a good idea to live in a home adorned with deadly spikes, whirling flame sticks, and tiny platforms moving back and forth over pits of lava.
And it's impossible to overstate the impact of Bowser's initial appearance. Navigating the world-ending castles was tough enough without Bowser's fireballs blasting toward Mario from off screen. The build-up was unbearable, and with the graphical power of the NES the payoff was worth it. The spikes on his back, his shark-like teeth, and his sneer made him the first genuinely threatening boss in history. Sure, these days he doesn't look quite as impressive. But he shot hammers out of his back, and that has to count for something.
- Mitch Krpata