Let's face it: there's no such thing as a completely, 100% original idea. All artists steal from other artists, and any good artist will admit it. Even George RR Martin's epic fantasy A Song of Ice and Fire (Game of Thrones) is basically the retelling of the actual War of the Roses with a bunch of Tolkien and other authors' fantasy elements thrown in.
That doesn't mean it's okay to completely plagiarize something, as The Simpsons have accused Famiy Guy of doing over and over again, but it does mean it's okay to build on a previously built idea. South Park has even called itself out, saying, "Simpsons did it! Simpsons did it!" in season six. It seems like most animated shows have a rivalry when it comes to who did what first, but when you look at all media, all you see is regurgitation of the same few plots with new twists on them--some of which are so minor that it still results in a very similar plot.
Do you think any of these shows intentionally plagiarize one another? Share your thoughts in the chat.