To be fair, the show is ending at like the exact point the comics ended. It's just the show introduced a lot of other shit.

In the comics, it was basically the Governor, then Terminus (well they were different in the comics), Negan, The Whisperers, and then the Commonwealth.

The show added the Grady Hospital group, the Wolves and the Reapers, and also prolonged the Saviors must more than they needed to. Also the Commonwealth wasn't as villainous in the comics as they appear to be in the show - really more complex and flawed, but not inherently evil