You know what I love more than almost anything else? An episode of a show told from the point of view of a supporting character, rather than the lead.

These episodes are so often TV treats. There's nothing more fun than getting to see how the supporting players perceive the characters who are normally the leads. It's a great reminder that everybody imagines themselves as the protagonist of their own story — we're all the supportive friend or the kooky coworker or the nosy neighbor to somebody else.

I'm not just talking about episodes that give a major storyline to a supporting player so the stars of the show can have a lighter workweek. I'm talking about episodes in which the entire show seems to shift to become about a different character. For one week and one week only, that character gets to be the star.

Putting the supporting characters at the center of the story enlivens things about the series that might have grown rusty. It gives the series a chance to break out of its most hidebound formulas. And at its best, it gives us a new perspective on characters we thought we knew, so we might get to know them even better.

Here are nine great supporting-character showcases, bookended by two recent examples.

What makes "Five-O" so remarkable isn't just the stunning work of Jonathan Banks as Mike Ehrmantraut, a former cop who's now flirting with the other side of the law. No, what makes it so remarkable is that fans of the character had to wait so long to get any real hint of his backstory beyond "former cop."

See, Mike, like this show's title character, Saul Goodman (Bob Odenkirk), originated on another show entirely — Breaking Bad. So fans of that program made it all the way through that show's run with only the slightest hint about who Mike "really" was. And then, right in the middle of the spinoff's first season, they finally got the whole story.

What followed was heartbreaking and gorgeous TV, featuring a soulful performance by Banks, all the more informed by the history viewers had built up with the character. It showed how supporting character showcases can utilize the passage of time to create maximum emotional impact.

Though M.A.S.H. didn't invent the supporting-character showcase, it certainly popularized it, returning to the idea with several supporting players throughout its run.

Of those episodes, the best was probably season five's "Dear Sigmund," which delves into the history and motivations of psychiatrist Sidney Freedman (Allan Arbus). Dr. Freedman only appeared in a handful of episodes of M.A.S.H., but he still became a viewer favorite, thanks to his acerbic wit and his compassion for his patients. In this episode, he writes a letter to Sigmund Freud that ably blends stories from his past with stories of his time on the warfront.

This type of episode has natural appeal for sci-fi shows — which often are forced to suggest larger universes without having the budget to depict them — and for large ensemble cast shows, which often have more actors than they know what to do with. Star Trek: The Next Generation fits both descriptions.

In "Lower Decks," from the show's final season, the series delves into a group of younger characters who are just coming up through Starfleet's ranks on board the Enterprise. The main cast of the series, meanwhile, is turned into a bunch of inscrutable authority figures — hard to figure out and even harder to appease. But "Lower Decks" also makes vital use of the fact that these unknown characters can actually die, for a powerful ending that another episode might not have been able to pull off.

The supporting-character showcase can be particularly fruitful on a show with voiceover narration. Take, for instance, My So-Called Life. In this episode, the narration shifts from protagonist Angela (Claire Danes) to her neighbor, the frustrated, nerdy Brian Krakow (Devon Gummersall). The series delves into his agonizing crush on Angela — who basically doesn't know he exists — while also digging into the life of a teenage boy who's not one of the popular kids.

It all concludes at a high school dance that's equal parts freeing and heartrending, as Brian pines for Angela, who pines for another, all while an entirely different girl has her heart broken by Brian. Ah, high school.

Perhaps the best trick The X-Files ever played on its audience was to devote an entire episode to the Cigarette Smoking Man (William B. Davis) — a major figure in the government conspiracy to cover up alien contact with humankind — and then make it mostly about his frustrated career as a writer of potboiler novels. Fans at the time were livid, but the episode has gone on to become a classic, both for its weird take on the show's backstory and for its exquisite filmmaking.

The central idea of the episode is also in keeping with the show's themes. If the protagonists can't ever get the truth about the aliens, why should their antagonist get what he wants? Nobody on The X-Files can ever get ahead, and that very often causes them to do incredibly awful things.

This might be the prototypical supporting-character showcase, the one everybody points to as one of the finest — if not the finest — examples of the form. In it, the world is about to end, as happens so often on this show, and everyone's off to battle the horrible monsters — except for comic-relief sidekick Xander (Nicholas Brendon), who has the night of his life when Buffy (Sarah Michelle Gellar) sends him off on a pointless errand so he won't get in the way.

This leads to Xander losing his virginity, stopping some zombies, and having the kind of story a supporting character can only have once he gets away from the main character. Adding to the fun are the occasional cuts to what Buffy and her friends are up to, which purposely heighten the ridiculousness of the show's storytelling so that it might make fun of itself, just a little bit.

Scrubs was another series featuring lots of voiceover narration, in this case from Dr. John "J.D." Dorian (Zach Braff). But the series got out of J.D.'s head frequently during its nine-season run, with the best example being this episode that turns things over to Dr. Perry Cox (John C. McGinley), the man J.D. would love to have as a mentor — and who would love nothing more than to have nothing to do with the kid.

Scrubs had built up Cox's machismo and rage issues to such a mythic level that nothing could have ever explained him entirely in just a half hour of television. But "His Story" makes a surprisingly good effort, as Cox's therapy sessions spill out into the rest of the hospital — and push J.D. out of the narration spot for one week.

Person of Interest already had a bit of a reputation for breaking with its format when "Relevance" aired, but this episode really threw fans for a loop. Suddenly the show wasn't following a band of rogue crime fighters operating off the grid, but rather a group of government agents hunting down terrorists — who soon find their lives in danger because they Know Too Much about the show's central conspiracy. Eventually, their paths intersect with the series' regular characters.

It's a great, action-packed hour of TV, and the character of Shaw (Sarah Shahi) became a series regular, so great was her impact upon the show. It still stands out as a series highlight, and an example of how a supporting-character showcase can effectively raise questions about a series' world and history.

Our other recent entry to this list, "Teacup" opens with series protagonist Josh (Jay Baruchel) scoffing about how much easier women have it than men when it comes to dating. As always on this show, however, the joke's on Josh, as the episode immediately cuts to his sister, Liz (Britt Lower), recently dumped by her longtime boyfriend and uncertain of how to proceed with her life. The guys she finds are either boring, gay, or literal robots, and the series dramatizes her fears in scenes that walk the line between sketch comedy and sitcom.

The core of the episode, however, gets at the series' deeper themes. The professionally successful Liz knows that the idea women can't have a career and a love life is inaccurate, but that doesn't stop her from feeling all of that societal pressure. Nobody has it easy when it comes to this stuff, as the episode's final scene, which unites Liz and Josh in a late-night chat, makes clear.

But "Teacup" suggests something else the supporting-character showcase sometimes does — that if this show were about Liz, it might be more interesting. It's not that the show is bad when it's about Josh. It's just that his story — young, single dude trying to find love — is a very familiar one the series has spiced up with fitful success. Granted, "professional woman approaching 30 and feeling a little bit guilty about how much she's worrying about that" is also a pretty common story to tell, but "Teacup" at least leaves you wondering, for a little bit, what this show might look like with Lower at its center and Baruchel stopping by every so often to offer advice.