Fans of Angel, the spin-off series to Buffy the Vampire Slayer had a lot of opinions about the show's cliffhanger of a series finale; the reason why Joss Whedon's show got canceled after season 5 is even more interesting.
Debuting in 1999 on The WB after Angel's season 3 departure on Buffy the Vampire Slayer, Angel both continued and expanded the Buffyverse, allowing characters from Buffy to find new potential—and better character story arcs—on the spin-off. Though the show revolved around the titular character, Angel (David Boreanaz), it expanded on a much larger universe and centered around the realistic setting of Los Angeles rather than the fictional, Hellmouth-based Sunnydale, California. This setting change not only allowed for more realism, but allowed Whedon and his writers to explore the gritty, crime-laden underworld of the city's seedy underbelly that was practically littered with demons.
Angel was not only a stark contrast from Buffy in terms of him being a brooding, dour ringleader, but the show took a darker premise and made him out to be almost Batman-esque in terms of his desire to intervene and "help the hopeless" with his team at Angel Investigations, a private investigating firm that specialized in doing battle with those who found themselves under demonic influence or in harm's way due to some supernatural threat. It took what worked for Buffy the Vampire Slayer—a "monster of the week" format, Whedon's signature humor, and lovable characters—and managed to become another success for The WB. Even so, it was canceled, which came as a shock to fans, as it hadn't seen a decline in ratings or viewership, and in the lead-up to season 5, seemed to have a lot more story to tell.
Why Angel Ended After Season 5
David Fury, one of the show's producers, spoke on the real reason behind Angel's cancellation in 2004: Joss Whedon pushed the network for an early renewal, and they didn't go for it. While it seems like a logical move for a showrunner to make, given not only Angel's success, but the fact that he was able to give a more singular focus to the show after Buffy the Vampire Slayer wrapped with season 7 in 2003, The WB didn't want the pressure of making a decision so early because they were entertaining other pilots, and some have speculated that the network might not have wanted to spend the large sum required to support another season of an older, more established show.
According to Fury, part of The WB's decision was "a power play".
"There was a power play that happened that just didn't fall out the way they wanted it to. We wanted to get an early pick-up, we didn't. In fact we forced them to make a decision, and with his hand forced he made the decision to cancel us."
Fury stated that it was Jordan Levin—who was the network head at the time—who made the call after Whedon inquired about early renewal; others have since stated that this was a mistake. Prior to cancellation, there were plans for future seasons. Because Angel was canceled early, there weren't any concrete plans, but some of the ideas that were rumored involved Illyria (Amy Acker) becoming more like Fred, Willow and Oz having larger roles on the show and returning in some capacity, and dealing with the direct aftermath of the events of the series finale, "Not Fade Away". Harmony (Mercedes McNab) also was poised to become a main character, though her larger role is unknown.
Whedon and the other writers have stated that season 5 of Angel would have been different with renewal for season 6; they made some of the decisions in the show's last season to tie up loose ends and tried to deliver a satisfactory ending, although according to Fury, renewal would have been "guaranteed" if they had waited just a little longer to ask.