Brave Belt > Bachman-Turner Overdrive
The Golliwogs > Creedence Clearwater Revival
The Warlocks > Grateful Dead
The New Yardbirds > Led Zeppelin
The Quarrymen > The Silver Beatles > The Beatles
The Who, in a bizarre twist, changed their name to the High Numbers in 1964 and released a single, “Zoot Suit.” When it failed to chart, they changed their name back to The Who.
A lot of bands change their names before they become really successful. The OP’s asking about bands that made it pretty big and then changed their names. I’m not sure if George Clinton’s bands qualify, but I’ll throw them out there. First there were The Parliaments and Funkadelic, then it became Parliament and Funkadelic, and I think the official name is now The P-Funk All Stars, but people call them Parliament-Funkadelic or P-Funk just as often.
Heh - we do that too.
Teddybear Suicide > Mouse Rat > God Hates Figs > Department of Homeland Obscurity > Flames for Flames > Muscle Confusion > Nothing Rhymes With Orange > Everything Rhymes With Orange > Punchface Champions > Rad Wagon > Puppy Pendulum > Opossum Pendulum > Penis Pendulum > Hand Grill Suicide > Angel Snack > Just The Tip > Threeskin > Jet Black Pope > Mouse Rat (again) > Scarecrow Boat…They finally settled back on Mouse Rat.
I agree with most of your post, except that the first ELO album was titled “No Answer.” According to legend, this title was based on a clerical error, but it IS the title on the album cover.
I’m looking at the label on the LP as I type. It says:
Australian band of the 70s / 80s:
Sherbet >> The Sherbs >> Highway (for the US market)
Them was the days…
According to Wiki
I guess a lot of the name changes occur when a key band member leaves or dies; was there a particular reason that the Byrds changed their name to McGuinn, Clark and Hillman? It’s not like they had a stable line-up for much of their recording history. After Jerry Garcia’s death, he Grateful Dead toured as the Dead until 2009.
Lynyrd Skynyrd briefly recorded as Rossington Collins, until a Ronnie Van Zandt relative joined and they returned to their more marketable name.
Sometimes, when the Member That Matters leaves, he takes the name with him, leaving the cast-off bandmates to soldier on under a different name: Stray Cats became Phantom, Rocker and Slick, Talking Heads became the Tom Tom Club (and eventually the Heads; not sure how Jerry Harrison figure into that), GnR became Velvet Revolver, Jane’s Addiction functionally became Porno for Pyros, some configuration of Camper Van Beethoven became Cracker, etc.
Ian Astbury left Southern Death Cult and formed Death Cult, which morphed into The Cult.
The rest of Southern Death Cult became Getting the Fear, among other names, and one of them went on to form Fun-Da-Mental
Puff Daddy, P. Diddy, Diddy Dirty Money. Very unusual for someone at the top of his niche change his name so drastically.
Prince and the Revolution, that weird glyph, Prince.
Eric Clapton let a truckload of one-off bands, any of which would have sold better under the name Eric Clapton.
Panic! at the Disco dropped the bang when they tried to become a more “adult” band with the album Pretty. Odd. Then, when the faction of the band that was pushing this change in direction left to form The Young Veins, they put back the ! character and resumed making more… well, let’s say non-baroque music.
Green Jello --> Green Jelly
After their “Three Little Pigs” song became popular, Jello pointed out a trademark issue with the band’s name.
Diddy is still Diddy. Diddy Dirty Money is the group he’s in with the two girls.
The Detours --> The Who --> The High Numbers --> The Who
Tom & Jerry --> Simon & Garfunkel.
They weren’t supposed to be one-offs. Blind Faith was supposed to be his next band, but that wasn’t the musical direction he wanted to go in, and Derek and the Dominos fell apart because drug addiction (mostly his).
Can I ask, one more time, that these bands have at least one top 40 hit under each name? Because changing your name when no one knows who you are isn’t really that big of a deal.
The Originals → Thamesmen → Dutchmen → Ravebreakers → Doppel Gang → Silver Service → Bisquits → Love Bisquits → Tufnel-St. Hubbins Group → Spinal Tap
(Source: Rocklopedia Brittanica)
ETA Biggirl’s request about Top 40, I’m not sure Tap qualifies then. According to the Rocklopedia Brittanica, “Though neither a critic’s nor a public favorite, Spinal Tap continues to fill a much needed void.” Still, there you are with name changes. 
*Small Faces *became *Faces *(with some lineup changes). They had hits under both monikers.
The awesome Burn The Priest released a demo and a couple of split albums, then finally released their debut full-length in 1999. Sometime in the next year they decided to rechristen themselves Lamb Of God before releasing 2000’s New American Gospel.
After that they slowly began to suck.