(Julee Cruise: Andrew Toth/Getty Images for New York Fashion Week, Hatsune Miku: Crypton Future Media, Inc. www.piapro.net Illustration by KEI, Crazy Frog: WENN Ltd/Alamy Stock Photo The Chipmunks: Photo 12/Alamy Stock Photo, The Archies: Pictorial Press Ltd/Alamy Stock Photo, The Monkees: AP, “Let It Go”/Elsa: Disney, Ziggy Stardust: Brian Horton/AP, Gorillaz: J.C. Hewlett)

In the noisy jungle of pop music, many artists speak their truth by pretending to be somebody else. Singing from the perspective of an alter ego has become standard practice for the likes of Lana Del Rey, the Weeknd, Lady Gaga and every rapper whose stage name doesn’t match what’s printed inside their passport. A few exceptionally multitudinous souls have even gone to the trouble of assigning alter egos to their alter egos: Nicki Minaj becomes Roman Zolanski, Eminem transforms into Slim Shady, Kool Keith mutates into Dr. Octagon, and on and on.

Still, we rarely lose track of who’s who. Perhaps that’s because adopting an alias simply grants a pop star permission to explore different realms of the self — the more they can express from a pseudonymous point of view, the more they can tell us about who they really are. Or maybe it’s just that music itself is a kind of sonic fiction, so it feels natural when it comes flowing from the mouth of an imaginary character.

Either way, the possibilities begin to multiply when we’re listening to the work of fictional musicians — that is, when the musicians don’t exist in real life, but whose music does. Most of the time, these imaginary musos originate as characters in movies or television shows, and their music fundamentally exists to help advance a story being told on screen. Sometimes they’re human (the Partridge Family, Spinal Tap, the cast in most Broadway musicals), sometimes they’re not (the original animated Josie and the Pussycats, Kermit the Frog singing “Rainbow Connection,” the characters in most Disney cartoons).

And while fictional musicians are commonplace in pop culture, we rarely pay any mind to the spectacular fact that their music leaks out of a fictional space and becomes a part of reality. Why isn’t this more astonishing to us? Probably because most of the songs that survive this freaky metaphysical transition aren’t all that freaky in and of themselves. And that feels like a wasted opportunity.

So how should we measure the work of fictional musicians? We could start by weighing the music’s novelty against its artfulness, and its familiarity against its strangeness. I’ve chosen nine fictional acts to put to that test — not because they’re the greatest make-believe pop acts to ever (not) exist, but because certain aspects of their work initially made the line dividing fiction from reality go fizzier than usual. This is fictional music that might help us better understand the breadth of what’s already out there, and what could still be.

And yes, this graph could be plotted on a three-dimensional ball to better account for the zones where novelty becomes artful and familiarity becomes strange. A lot of great pop music reaches for those mysterious spaces. More fictional music should.

The Archies

Penned and performed by a team of session musicians, the Archies’ bubble-gummy rock songs weren’t very strange, but the group’s success certainly was. When the fictional cartoon teenagers reached No. 1 with “Sugar, Sugar” in 1969, a garage band that only existed in two dimensions was suddenly vibrating the three-dimensional air from the top of the charts. (Wilson Pickett released a cover of “Sugar, Sugar” in 1970, but he only got it up to No. 25.)

The Chipmunks

Before the Chipmunks were bankable cartoon characters — or even chipmunks — they were a sound. In 1958, songwriter Ross Bagdasarian had figured out how to record his singing voice at half-speed and then play it back an octave higher as a high-pitched chirp, scoring a big novelty hit in 1958 with “Witch Doctor” (refrain: “Oo-ee-oo-ah-ah-ting-tang-walla-walla-bing-bang”). Later that year, when he decided to assign these bizarre vocalizations to a fictitious trio of rodents via “The Chipmunk Song (Christmas Don’t Be Late),” it all clicked with listeners, blooming into an entertainment franchise that still exists nearly 60 years later.

Crazy Frog

Crazy Frog started as a sound, too — the sound of a Swedish teenager impersonating a moped engine in 1997. A recording of that onomatopoeic gurgle — ding-ding-da-da-ding-ding — began to circulate online, and in 2003, another Swede drew an animated cartoon character to go with it. In 2004, the vocal vroom-vroom became a massively popular ringtone, and in 2005, Crazy Frog was sputtering out songs aimed at the pop charts. Today, those songs sound perplexingly catchy and maybe even influential — they seem to foreshadow the Auto-Tuned yawp of Young Thug, the incessant chatter of the Minions and plenty of digitally processed babble in between.


The English virtual band Gorillaz. (J.C. Hewlett)

Julee Cruise in “Twin Peaks”

Director David Lynch and his trusty soundtrack composer Angelo Badalamenti wrote and produced Cruise’s billowy, stand-alone 1989 debut, “Floating Into the Night,” after working with the singer on Lynch’s 1986 film, “Blue Velvet.” But as exquisite as this music was in its own right, it became inextricable from “Twin Peaks” after Lynch called on Cruise to perform in two episodes of his deeply imaginative television series. Most films and TV shows usher fictional songs into reality, but this was an inversion: The director effectively sealed the singer’s realest songs inside a fictional universe.

Gorillaz

If the Archies proved that cartoons could be a band, Gorillaz proved that a band could be cartoons. Comic book artist Jamie Hewlett sketched the characters and Damon Albarn of Blur wrote the songs, and today, Gorillaz stands as the most successful “virtual band” of the 21st century. But musically, after five well-regarded albums, the project seems to primarily exist as a platform for Albarn to scratch his collaborative itches — the band has worked with everyone from Vince Staples to Mavis Staples. Why does that require Albarn to pretend he’s a cartoon? (See for yourself when Gorillaz perform at Merriweather Post Pavilion on Monday.)

“Let It Go”

For better or worse, this power ballad from Disney’s “Frozen” was absolutely inescapable in 2014, and it scaled the charts in two separate iterations — the dramatic version that appears in the film (sung by the character Queen Elsa, voiced in song by Idina Menzel), and a brisker version sung by plucky pop singer Demi Lovato. If anything, the ubiquity of “Let it Go” proved that fictional music is flexible: A tune that belongs to one animated character could be sung by two distinct human voices.


From left, Michael Nesmith, Peter Tork, Davy Jones and Mickly Dolenz of the sixties band The Monkees. ( Holger Bennewitz/Reuters)

Hatsune Miku

For a glimpse into the future of fictional music, gaze into the saucer-shaped eyes of Hatsune Miku, an animated character created by the Japanese software company Crypton Future Media. The company’s singing synthesizer application allows users to compose music for Miku to “sing,” and in her native Japan, the character has become a new kind of virtual celebrity, performing concerts as a three-dimensional projection. Here in the United States, one of Miku’s most promising collaborators is Laurel Halo, a plain old human being responsible for some of today’s most intriguing avant-garde electronic pop. Tomorrow looks weird and bright.

The Monkees

The most astonishing thing about fictional music is how effortlessly it slips out of its narrative context to join us in reality. In the case of the Monkees, the pretend rock band singing those songs became real, too. And that’s wild! Imagine if, say, an actor playing Batman decided to leave Hollywood and give vigilante justice a try. But back in the ’60s, once the Monkees’ music became more popular than their television show (a comedy about the misadventures of an unsuccessful rock band, funny enough), there was no turning back.

Ziggy Stardust and the Spiders from Mars

Another inversion: Just as the Monkees learned to be real, David Bowie yearned to be fake. What a genius. But what many imitators of Bowie’s shape-shifting too often forget is that he wanted his most celebrated alter ego to be more than human — a pansexual space alien for starters, and a rock-and-roll icon for the ages.