Who is Negan? Is that some zombie leader?
Pretty close.
Negan is a fictional character in the comic book series The Walking Dead. He is the leader of a group of roughly 70 survivors in The Sanctuary, called the Saviors, a group that steals from others.
https://en.wikipedia.org/wiki/Negan
Negan is the new villan on the Walking Dead. During last season, the main characters kept running into Negan's people. On the last episode, the main characters are finally captured by Negan, and one of them is executed.