Not all musical episodes are created equal some TV shows stage a one-off interlude to mark a milestone, like How I Met Your Mother‘s 100th episode; some rely on cover songs to give their writers a break, like That ’70s Show and Grey’s Anatomy but occasionally, ambition and execution align to create something special, an installment that services the characters, advances the plot and sates our hunger for toe-tapping original tunes and jazzy dance numbers.
Thankfully, The Flash‘s musical crossover with Supergirl (which airs March 21 on The CW), falls into the latter category.
In addition to featuring pivotal character development for both heroes, the episode features a mix of pitch-perfect covers and two original songs (one penned by La La Land lyricists Benj Pasek and Justin Paul, the other by Crazy Ex-Girlfriend‘s Rachel Bloom), all of which will earn a permanent place on your playlist.
It definitely doesn’t hurt that both shows boast an enviable array of singing talent: The Flash star Grant Gustin and Supergirl‘s Melissa Benoist are both Glee alums as is guest star Darren Criss, who plays the episode’s antagonist, Music Meister while Victor Garber, Jesse L. Martin, John Barrowman, Jeremy Jordan and Carlos Valdes have all appeared on Broadway, making the musical kind of a no-brainer.
In honor of SuperFlash‘s “Duets,” Mashable took a look back at 10 of the best musical episodes that came before it.
10. Psych – “Psych the Musical”
This ambitious (but unnecessarily protracted) two-parter was years in the making, having initially been planned for the sixth season, but eventually airing in Season 7. It received mixed reviews from critics but deserves props for its sheer sense of scale, with 12 original songs and several elaborate dance numbers.
9. Xena: Warrior Princess – “The Bitter Suite”
Three years before Buffy‘s “Once More with Feeling” blew our minds and broke our hearts, Xena decided to help its own titular heroine work through her issues with song. The episode saw Xena and Gabrielle transported to the Land of Illusia to confront their anger and betrayal after Gabrielle’s daughter murdered Xena’s son (no biggie, right?). It was nominated for two Emmys for the original songs “Hearts Are Hurting” and “The Love of Your Love,” and was well-received enough to prompt a second musical episode two years later.
8. Clone High – “Raisin’ the Stakes: A Rock Opera in Three Acts”
Featuring Jack Black as a raisin-pushing villain who gets the entire school addicted to hallucinogenic dried fruits, Phil Lord and Chris Miller’s comedic tour de force is a trip in every sense of the word a raucous and surrealistic yarn that’s so deeply weird and layered with subtext, the songs will seem like the sanest part.
7. Futurama – “The Devil’s Hands are Idle Playthings”
Originally designed as the series finale (before the show received an unexpected revival courtesy of Comedy Central several years later), this was Futurama at its best: sharp, sly and surprisingly sweet. In it, Fry makes a deal with the Robot Devil to become a musical maestro and impress the enduring object of his affections, Leela; leading to an elaborate opera segment and a poignant final scene that served as a fitting send-off for the series for a while, anyway.
6. Community – “Regional Holiday Music”
A delightful Christmas episode and a delicious parody of Glee (right down to a song literally called “Glee”), “Regional Holiday Music” drafted Saturday Night Live‘s Taran Killam as Greendale’s deranged glee club instructor Mr. Rad, and deployed five original songs to skewer everything from Glee‘s penchant for covers to its trademark a cappella transitions between scenes.
5. It’s Always Sunny in Philadelphia – “The Nightman Cometh”
No other musical on this list features incestuous subtext, the strong musky power of true love or firm reassurances that one of the characters is definitely not a child molester, so at least “The Nightman Cometh” has that going for it? (It also became a live musical show IRL, which is hard to beat.) Despite the fact that the titular musical within the episode isn’t supposed to be a comedy, according to Charlie, you’d be hard pressed to find one that gives you more laughs inadvertent or not.
4. Supernatural – “Fan Fiction”
Supernatural’s 200th episode was a literal love letter to the fans paying homage to the fandom’s boundless devotion and creativity with a meta twist when Sam and Dean stumble upon a staging of “Supernatural: The Musical!” devised by fans of the cult book series that’s secretly based on their lives. The show features three wickedly original songs that overflow with in-jokes and winks, but the real showstopper comes from the chill-inducing rendition of Kansas’ “Carry on Wayward Son,” which has become an unofficial theme song for the series over the course of its run.
3. The Simpsons – Simpsoncalifragilisticexpiala(Doh!)cious”
The Simpsons is practically perfect in every way when it comes to conceptualizing musical numbers, but its Mary Poppins homage is one of its finest half-hours going all in on the parody by introducing a sprightly British nanny who soon realizes that there’s no spoonful of sugar strong enough to help her deal with the Simpson family.
2. Scrubs – “My Musical”
Widely considered one of the best episodes of Scrubs and for good reason this poignant and hilarious installment managed to cram in 10 musical numbers (including one about poo) while emotionally grounding a potentially wacky conceit with a believable (and real) medical condition providing one of the few logical justifications for a musical episode in TV history. It was nominated for five Emmys and won for Outstanding Sound Mixing.
1. Buffy the Vampire Slayer – “Once More with Feeling”
Everyone from The Flash/Supergirl showrunner Andrew Kreisberg to Scrubs and Clone High‘s Bill Lawrence has credited Joss Whedon’s game-changing opus with inspiring their own musical experiments, and its impact can’t be overstated. The episode was a pivotal one in the show’s narrative with Buffy revealing that her friends had inadvertently pulled her out of heaven instead of rescuing her from hell, as they’d assumed which left her feeling disconnected from her family and her duties as Slayer. “Once More” perfectly demonstrated why the best “gimmick” episodes are those that propel the plot and characters forward. It’s not just the best musical episode of all time it’s arguably one of the best hours of television, period.
The Flash‘s musical crossover with Supergirl, “Duets,” airs Tuesday, March 21 at 8 p.m. on The CW.