Featured In: Super Metroid (1994)
Ridley is undoubtedly Samus' greatest nemesis, even more so than Mother Brain. The guy killed her mother right in front of her and his Space Pirate minions forced her father to sacrifice himself to stop them. He's been featured in every game except for Metroid II, Prime 2, and Hunters, giving him the honor of the most frequently appearing villain.
You then track him down to Planet Zebes and near the end of the game you encounter him once more. What makes this fight interesting is the simplicity of it: bosses like Kraid require you to find his weak point, Phantoon can only be damaged at certain points, etc. Not so with Ridley.
Literally the only part of Ridley that can't be damaged is his tail. Also, he can be damaged by nearly everything you've got: Missiles, Super Missiles, Charge Beam, and even the Power Bombs damage him. What makes him challenging is his sheer endurance; you're going to be using A LOT of ammo, if not all of it.
He spends most of the fight flying randomly, only to swoop down to smack you with his spiked tail. Sometimes he'll pluck you straight off the ground, or even try to repeatedly make a Samus kabob with his tail, Pogo stick style.
Once you've dealt the final blow, Ridley explodes in an elaborate display, ending the Space Dragon's threat forever. Or does it...? Perhaps he won't show back up on this list, of will he?
This fight was the bane of my existence as a child. I remember having a heck of a time and feeling so accomplished every time I emerged victorious. It's still satisfying to this day. In fact, check out this video where (at the end) I kick his space dragon butt. Do it!
5) Neo Ridley (Metroid Fusion)
Neo Ridley is such a fun fight. I really loved this game, and this is one of my favorite fights in it. I always love Ridley fights, and this one is one of the best! Ridley is just such a fun villain with his bashing teeth, and sharp tail he stabs you with. Frustrating but so much fun!