There are plenty examples of hero-to-villain arcs in TV and film, but that's not the only place we find them — they also, unfortunately, happen in real life.
Reddit user u/do_u_liek_ButtSchexx recently asked just this — "Who is your example of 'You either die a hero, or live long enough to see yourself become the villain?'" — and there were some super interesting replies.
Warner Bros. Pictures
Here are 17 people who ended up becoming pretty big villains, despite starting out as heroes!
Note: Some of these submissions contain mentions of rape, abuse, and animal cruelty.