CASTLE ON TNT—Castle is no longer airing on TNT at the present time. I’m not sure if it will be returning to the schedule anytime soon, if at all. This could be a “pause” in the airings while TNT cycles through shows in its library. It’s also possible their licensing has run out and they chose not to renew it. This would make the show available to other cable channels (such as USA, We, ION, etc.). But the cost might scare some away.
As for TNT, the show has had a rough go recently. The ratings have steadily dropped over the past two years. The cable network has moved it around, reducing airings and went to a limited “one-a-day-week” schedule earlier this year hoping it would “boost” it up, but has failed to do so.
Like a lot of series, reruns tend to wear thin over time. And if shows in syndication aren’t pulling in the ratings, there’s little reason for advertisers to buy time on those shows. Castle has fallen victim to that line of reasoning.
The show is still airing on over-the-air syndication (such as your local ABC station). And it is of course, available through iTunes and Amazon.