For a petty reason, Syndrome became a serial killer and put the whole city in danger and destroyed the plane on which the children were all due to the fact that Mr. Exceptional rejected him and then for a just reason. The Syndrome started hysterical and started running. Also Sir Miles Axelorod had a foolish reason too, as he is already rich. Goulfinger and Eliot Carver tried to commit mass murder to get even richer, even though they are both rich already.

Mysterio from the MCU orchestrated several events that resulted in mass murder just cause Tony Stark fired him

Some of the Rwby villains are petty like Dr Arthur Watts who joined Salem because he was jealous that Ironwood chose Pietro Polendinas work over his own and made him feel “disgraced”.

Adam Taurus who wants to ruin Blake’s life and destroy everything she loves all because she walked away from him and left the White Fang behind because of their increasing brutal actions.

Eh, Salem isn't PE.

Whoops! my mistake, I’ll just edit her out.

Reverse-flash by a mile

I think it's too obvious for "petty" to count as a category. The same goes for "Equally hostile", "Selfish", "Irredeemable", etc. Pure Evil villains who aren't under Faux Affably Evil are straight up hostile from start to finish.