Cancellation of Futurama

In 2003, when the production company of Futurama were waiting for FOX to order a fifth production season in wake of the fourth production season's production being almost finished, no call came, effectively labelling Futurama as cancelled, ending the show's original run.

In early 2006, after successful DVD sales and popular syndication on Adult Swim, 20th Century Fox Home Entertainment decided to order four films as a fifth production season.

Causes
The first and foremost cause of FOX refusing to order new episodes after four production seasons is attributed to the price of show and the decreasing popularity of the show. Despite Futurama's pilot episode, "Space Pilot 3000", being the most watched pilot episode on FOX when it aired, the show had been decreasing slowly in popularity over time, and FOX was disappointed in the show, which they had assumed could gain a popularity like their other show, The Simpsons, and even within FOX, arguments arose regarding whether they had kept Futurama alive for too long.

However, despite FOX's own disapproval of the show, FOX themselves was to blame for the decreasing viewership of the show. Indeed, its popularity had not gone down, but rather the amount of viewers it had, as the show had moved to a less popular timeslot since "I, Roommate". In addition to the less popular timeslot, it was also highly unstable, as FOX would often put off an episode for another event, e.g. sporting or news reports. This made new episodes highly unpredictable for viewers.

Indeed, FOX's unstable airing eventually lead to the airing of five broadcast seasons, rather than the four produced. Not only were episodes aired out of order, but examples like "The Route of All Evil" had to be pushed back two entire seasons. This unpredictable nature, the unpopular timeslot eventually lead to the demise of the viewership and the show's popularity in terms of numbers.

Despite the fact that "Space Pilot 3000", the pilot, was a very popular pilot episode in terms of viewership, as well as the second episode, "The Series Has Landed", whose popularity was attributed to the Sunday line up it was in, with the lead-in show of The Simpsons as well as  after the show, FOX decided to move the show to its Tuesday line up instead, beginning with "I, Roommate", which as expected hurt the show's ratings. And the show continued to dwell on these ratings for four broadcast seasons.

Cancellation
Technically, Futurama was never cancelled, it was simply not renewed. In usual production, the purchase of an additional production season, usually comes near the end of its current production season, as to not put the production company on hold for too long, which would eventually cause a loss of money. By 2003, the fourth production season was basically finished, and the producers were waiting for 20th Century Fox Television to call with an order of another season. However, the call never came.

However, Fox had alerted the production company, that "The Devil's Hands Are Idle Playthings" could be the last episode they'll ever make, as such its production was developed with that in mind, and at the very least was written as a season finale. It should later turn out to be that series finale, they had feared.