Sonic the Hedgehog and His Enemies
Through his illustrious career, Sonic the Hedgehog has met with many an adversary. Ranging from the usual baddies throughout the levels to the boss enemies. Most of them are quite forgettable when compared to the main few enemies that Sonic has had to deal with. There are actually only three or four memorable characters when it comes to Sonic beating someone up.
It all started with Dr. Ivo Robotnik, so it is only fair that this article starts with him. An evil genius, Dr. Ivo Robotnik has but one driving desire in this entire universe. That desire is to take over Mobius (Sonic's home planet) and make everyone do his bidding. This is of course unacceptable to Sonic and he foils Robotniks's plans each and every time. Sonic taunts him by calling him egghead and chases him to outer space to stop him from wrecking havoc on his planet.
Robotnik is also one of the most intriguing characters within the game. Except for his 'take over the world plans' nothing much is known about him. We know what he looks like and we know that he is a doctor. But beyond that we know nothing. Like where he gets all the money from to build all those robots.
Robotnik being the mastermind he is, he outsources his work to a robot called Metal Sonic. This is an evil robotic twin of Sonic and does bad things in Sonic's disguise. He is of course stopped by Sonic who grinds him down. Metal Sonic is actually the predecessor of Mecha Sonic - another robot twin of Sonic built by Robotnik. The main concern here is the fact that Mecha Sonic tricks others in to believing that all that destruction is being caused by Sonic himself. The epic battle between Sonic and Mecha Sonic makes a lasting impression on all gamers who are Sonic fans and have played the games.
Mecha Sonic also paves the way for another super strong adversary - Knuckles the Echidna. As the last surviving member of the ancient race of Echidna, he is also the paranoid guardian of the Chaos Emeralds and the Master Emeralds. He is ready to fight anyone who looks like a threat to the emeralds he so jealously guards. Robotnik tricks him through Mecha Sonic and makes him believe that Sonic is the one who is after the emeralds.
The Echidna believes him and goes off to fight Sonic whilst Robotnik gets busy stealing the Emeralds for himself. Thankfully, the Echidna is not entirely devoid of intelligence and soon joins forces with Sonic to fight Robotnik. Knuckles is as dangerous an enemy as he is powerful as an ally. The relationship between the Echidna and Sonic could've been one of strong friendship amongst equals had the circumstances been different. But given his paranoid nature, it has always been a love-hate relationship. So he is not to be counted amongst the full time enemies of Sonic.
Thus, the criminals within the Sonic games also form a memorable part of the classic games.