The Robot Chicken. They really struck gold with Rick And Morty, where a scientist takes his grandson on adventures that span space and time - but often take a horrific mental toll on them both.
The show has produced a number of classic episodes, from "Meseeks And Destroy" to "Pickle Rick." The series was co-created by Dan Harmon (Community) and Justin Roiland, and it balances a unique blend of comedy, sci-fi and domestic drama. Season 3, for instance, has all the action and adventure of prior series but it also takes time to explore the negative effects Rick has had on his own family. Rick And Morty is set to return for season 4 in November 2019.
Probably one of the bleakest episodes of the show was season 1's "Rick Potion #9," where following his attempts to undo a mess that turned most of the world into fleshy monsters dubbed "Cronenbergs" - after famed body horror director David Cronenberg (The Fly) - Rick just decides to abandon that dimension and take his grandson Morty to a new one. This episode established how dark the show could go, with Rick deciding to abandon the rest of his family to a world of monsters because it was the more convenient choice. This decision has been brought up a number of times since, including on Rick And Morty's season 3 episode "Morty's Mind Blowers."
This episode is a riff on the Interdimensional Cable episodes of previous seasons, where the duo watch cable from other dimensions. The premise of "Morty's Mind Blowers" involves Morty exploring a room filled with bad memories he made Rick remove; needless to say, there's a lot of them. One key revelation of this Rick And Morty episode is that they've abandoned more than one dimension, where Morty accidentally discovered the world is controlled by super intelligent squirrels.
This memory begins with Rick building Morty a gadget that lets him hear the thoughts of animals like birds or ants, Doctor Dolittle style. It's pleasant at first until he overhears three squirrels, who are conspiring to destabilize the economy of Argentina so they can install a more compliant regime and they also plan to pick a new pope. This is when the squirrels realize Morty can hear them, and soon he and Rick are swarmed and they have to flee to a new dimension.
In addition to being a fun jab at conspiracy theorists, it's also genuinely a little creepy when the squirrel army starts to overwhelm Morty. Of course, it's doubtful the Rick And Morty squirrels will return - though anything is possible on this show - but it was another fun way to open up the endless bizarre mythology of the show.