1. The Dave Clark Five

There are two basic, obvious means of staying relevant. Musicians need to 1) license their music and 2) make it available. Simple, right? Well, the Dave Clark Five is the case study of what happens when a band tightly locks up its tunes and rights. You just do not hear the group's songs anymore, nor are they available on streaming. Go ahead, search. The Dave Clark Five, named for its drummer and featuring singer Mike Smith, are downright obscure. And we want to stress how HUGE this band was from 1964–67. It churned out 14 Top 20 hits. The Tottenham quintet appeared a whopping 18 times on The Ed Sullivan Show, more than any other British Invasion act. Warner Bros. released a movie starring the boys, titled Having a Wild Weekend in the States, directed by the guy who eventually did Deliverance. The Remco toy company even churned out Dave Clark Five action figures. And yet… if a Millennial can name one of their songs, it's a miracle.

Image: The Everett Collection

2. Paul Revere & The Raiders

In the span of months, in that 1966-67 sweet spot, the Raiders knocked out four Top 10 hits. Dozens of their songs charted, as the Boise-born band finally landed a No. 1 in 1971 with "Indian Reservation (The Lament of the Cherokee Reservation Indian)." Sporting colorful Revolutionary War outfits, the Raiders seemed to appear straight out of a cartoon. No wonder they were the rockers performing at the Penguin's election party in the campy Batman episode "Hizzoner the Penguin." If anything, the colorful wardrobe is perhaps what kept Paul Revere & The Raiders (202,000 Spotify listeners per month) trapped in its era. The band is just so of its era. Rock stars still aspire to look and sound like Jim Morrison. Nobody is out there dressing like George Washington while singing "Ooh Poo Pah Doo." Alas.

Image: The Everett Collection

3. Chad & Jeremy

Like Paul Revere & The Raiders, Chad & Jeremy popped up on Batman. Catwoman attempted to steal the duo's voices in "The Cat's Meow." The Caped Crusader spoiled her plans, naturally, and the band sang "Distant Shores" and "Teenage Failure." The two turned up on other sitcoms, too. The English folk-rocker appeared on both The Dick Van Dyke Show and The Patty Duke Show in a one-week span. Jeremy Clyde guest starred on My Three Sons, as well. All that screen time helped send ditties like "A Summer Song" and "Willow Weep for Me" high up the charts. Hipster filmmaker Wes Anderson helped bring "A Summer Song" back into the pop consciousness when he included it on the 1998 Rushmore soundtrack. But two decades later, the easy, breezy twosome is drawing a mere 104,000 listeners on Spotify.

4. The Cowsills

This family band from Rhode Island thrived through television and died by television. Led by their mom, Barbara, the six siblings appeared all over television, on everything from game shows (To Tell The Truth) to Ed Sullivan. In 1968, NBC cast booked Buddy Ebsen to feature in a TV special about the Cowsills, A Family Thing. Their name recognition helped the Cowsills (111,000 monthly listeners) send two tunes, "The Rain, The Park & Other Things" and "Hair," to No. 2 on the Billboard charts. At the end of the decade, Screen Gems approached the Cowsills about starring in TV series. There was one catch — the studio wanted to recast their mom with Shirley Jones. The kids said no, so a fictional band modeled after the Cowsills was whipped up from scratch. It was called The Partridge Family. The facsimile erased the need for the original and quickly superseded it.

Image: The Everett Collection

5. The Young Rascals

This New Jersey quarter scored three still-familiar No. 1 hits with "Good Lovin'," "Groovin'," and "Got to Be Free," one per year from 1966–68. That was enough to earn the band a place in the Rock and Roll Hall of Fame in 1997. But over the last two decades, the group has fallen into relative obscurity (226,000 listens per month), perhaps because people are unsure whether to call 'em the Rascals or the Young Rascals. (And maybe, just maybe, younger generations confuse them for the Little Rascals?) Again, clothing might be an issue. Dressing up like 19th-century schoolboys might have been cool at the time, but the Little Jack Horner look has fallen out of style.

6. Jan and Dean

Jan and Dean rode the wave of the surf craze in the early 1960s. Heck, the tall and handsome Los Angeles boys helped kickstart the trend. In 1963, "Surf City" became the first surf tune to top the charts. They were the Beach Boys before the Beach Boys, singing odes to sand and hot rods. But the Beach Boys evolved, dramatically and psychedelically, while Jan and Dean (219,000 monthly listeners) could never shake the Archie Andrews vibe, sounding like a relic of a bygone era of doo-wop and soda fountains.

Image: The Everett Collection