User blog comment:Alwaysmore2hear/Nominate Your Essential Villains for the 2018 FANDOM 100/@comment-24439896-20180911214641

Shocker from Kamen Rider.

Aside from being unique due to being an organization rather than individuals, Shocker is one of the primary codifiers of the "Monster of the Week" trope, with each episode of the show involving the organization sending one of their Kaijin monsters after the titular hero. Without Shocker, we wouldn't have villains like Rita Repulsa or really any Power Rangers villains.

Plus, Kamen Rider I don't think has ever had any villains in the top 100, so it would be really cool to have a villain from a franchise that isn't as publicized in the West.

Also, they're Nazis, and who doesn't love to have Nazis as the villains.

Here's Shocker's page on the Kamen Rider wiki if you want to learn more.