Top 10 Evil things he did to his colleagues

 Top 10 Evil things Jim did to his colleagues:

1. Ensured they have a bad health care plan (S1, E3): By refusing to lead the process of picking a health care plan himself, and by telling Michael that Dwight should do it instead, even though he knew Dwight would cut benefits. This helped alienate Dwight from his colleagues, encouraged everyone to hate Michael, and discouraged everyone from working hard.
2. Prevented Michael from signing important monthly documents (S2, E6): Michael should be signing important documents, that people's jobs potentially depend on, so it's a stressful day for everyone, but Jim goads Michael into fighting Dwight (at the Dojo), wasting everyone's time, and by doing this he is both encouraging Michael to procrastinate, and encourages further bullying of Dwight. He is also demotivating his colleagues, and encouraging them to forge Michael's signature.