Minor villains that're indirectly responsible for a lot of shit?

In the past, I've talked about major characters who leave behind a long legacy, even after they're gone. Here, let's talk about villains that're mere footnotes at the end of the day who, regardless, managed to cause so much damage with their actions.

Dane Gustavia/Carmelo Gusto in Ace Attorney Investigations 2. He only shows up in case 3, but the impact of his actions cannot be understated. For one, he's the reason Investigations 2 even happens, as Simeon is the son he abandoned, causing his turn to villainy. But even more than that, his murder of Artie Frost/Issac Dover practically kicked off the entire storyline of the first 3 games. The investigation would eventually culminate in the DL-6 incident, which served as the motivator for almost every major character in the original trilogy, such as Edgeworth being taken in by von Karma, Misty Fey having to leave her family and the resulting power struggle, and things such as Phoenix meeting Mia and becoming a defense attorney. All stemming from this one asshole chef.

Dario Brando in JoJo part 1. He doesn't get a lot of screentime, and dies before the first chapter/episode is even halfway done, but that's more than enough. The abuse he heaped on Dio molded him into the ruthless monster he would become later in life. In addition, the debt George "owed" him gives Dio access to not only education, but the Stone Mask, becoming an even bigger problem. All of this stemming from some drunk pickpocket.