Normal monsters aren't very exciting. While crucial to the early days of Yu-Gi-Oh they quickly earned the nickname 'vanilla' for being bland and only having the job of attacking or defending.
The anime did a great job at making normal monsters look exciting and relevant and a lot of decks in modern-day Yu-Gi-Oh should be thankful for how these iconic normal monsters were portrayed.
Decks that feature the Blue-Eyes White Dragon or the Dark Magician would certainly be less appealing if not for the ruthlessness of Kaiba or the kind-hearted Yugi Moto.
Every now and then a normal monster would rise up and push a particular archetype to the top of the metagame. New support tailor-made for a particular kind of normal monster would push the otherwise 'bland' card to its limits.
Just like with the '10 Most Broken Spell Cards in Yu-Gi-Oh', we'll be focusing on the entire competitive history of Yu-Gi-Oh. This means that while some of these normal monsters may be slightly out of date by today's standards, they certainly changed the way the game functioned at some point in time.