As of right now, I am one episode away from completing the first and only season of Constantine.
I got into it after the title character showed up in an episode of Arrow.
John Constantine is an exorcist. In each episode, he and his friends travel to places where spiritual occurrences have taken place. They must then battle against the dark forces.
Unfortunately, the series wasn't renewed after its first outing. It's a shame to be fair because I have found it enjoyable.
It's available on Amazon Prime if you'd like to catch it. There are only thirteen episodes!