While some aging TV shows add characters to stay fresh, The Simpsonsbuilt an entire episode mocking that sham (''The Itchy & Scratchy & Poochie Show''). Even welcome newcomers aren't spared: Frank Grimes is killed off in his first episode. EXTRAS The Simpsons: The Complete Eighth Season offers a standard collection of sketches, deleted scenes, and commentaries. On one, showrunner Josh Weinstein gushes about the Man in Black, who voiced a coyote, ''We made Johnny Cash make gnawing-a-guy's-leg sounds.''

