The Grateful Dead and Groovy Show was commissioned in 1975 about the Dead by popular makers of poorly-drawn cartoons, Hanna-Barbera.
In it,the Dead traveled around the country solving crimes with Groovy, their pet dog who could speak. It was never explained whether all dogs could speak in this universe or whether just one dog, and they happened to have it, and instead of making billions of dollars pimping out this super-dog, these fuckheads were washing their underwear in sinks because they lived in a van and played Hardy Boys.
Each of the Dead had superpowers that they displayed on occasion: Phil had super-hearing; Bobby was super-handsome; and Garcia had an alter ego, Captain Trips, whom he would hide in the bathroom and turn into except he never came out of the bathroom and now it smells funny.
The show was never aired.