My brother sent me a text message the other day, asking me an interesting question: how many bands can you think of that changed singers but kept going on with the same name.  He offered Van Halen, AC/DC, and Black Sabbath as examples.  I was at work, so I had plenty of time to think about this (my job these days is cashiering for a fast food place on campus during the 2:00 to 6:00 doldrums) and at first it seemed like this would be a fairly rare occurrence.  Very few things are as singular about a band as the singer - most people won't notice when a guitarist leaves a band, or a drummer, even though they may be replaced by someone with a very different style.  But even a very similar singers in style can have very different voices, and for a band to continue simply being recognized after such a change must be difficult.

But as we talked about it, more and more examples kept coming out.  10,000 Maniacs, Pink Floyd, Queen, Alice in Chains, Fleetwood Mac, Black Flag.  Goo Goo Dolls, depending on how you want to look at it.  We didn't even count bands that don't really have a single lead singer (the Beatles, the Band) or where someone else occasionally takes a lead vocal (the Cars, the Stones, the Who). 

Looking at it now, it seems like there are three types of bands that change lead singers:  the first, and most easily visible are those that get a new singer nearly the twilight of their career, primarily so the band can continue to tour, and maybe release the occasional new album.  Sometimes this is because the original singer is dead  (Lynyrd Skynyrd, Queen) or because the band wishes they were (Journey).  Again, this is primarily to cash in on nostalgia tours - new albums are fairly rare, and usually not terribly well received.  (The things people said about the Doors reunion, man!)

The second category is the one we were thinking of originally - a band changes singers mid career.  We thought this would be a fairly rare occurrence, but the success of my brother's original three shows it is possible: Van Halen, AC/DC, and Black Sabbath all pulled it off and went on to even greater success.  I'll even put 10,000 Maniacs in that group.  These moves tend to be amazingly polarizing, for obvious reasons.  In fact, anyone who replaces the singer in a popular band is likely to be called Sammy Hagar for a while at least.

But the third category might be the most interesting - bands who change their singer relatively early in their careers, so early in fact that later fans might not even be aware of the lineup change.  Pink Floyd, Genesis, and Fleetwood Mac all embody this.  What's interesting is that their early music often sounds like a completely other band that the later direction.  Partly this might be because in all three of these cases, the singers (and sometimes guitarists) who left were the main artistic force in the band, but also I think because the bands hadn't yet created a musical identity.  Genesis is clearly the odd man out here - their career with Peter Gabriel lasted a decade or so, but when he left, their stylistic change was huge.  Maybe because he had been the creative force in the band, unlike Van Halen, AC/DC, and Sabbath which were so clearly guitarist dominated.  Or maybe it was the fact that Collins came from within the band, rather than being an outsider, that kept him from becoming the original Hagar.

The Goo Goo Dolls are similar to Genesis in some ways - most newer fans don't realize that their bass player, Robbie, sang all the songs on their first album.  It was a long time before Johnny Rzeznik became their lead singer.  They also have the distinction of being the only band on this list where no one quit the band.

The original question my brother posed was "What are bands that changed lead singers but kept on with the same name" but in fact, it has been the corollary that seems rarer - bands that changed lead singer and kept on but changed the name.  In fact, it seems like the most likely course of action is simply for the band to break up.  Carrying on with the same name is hard, but nowhere near as hard as starting over completely.  In fact, I can only think of one band that did - New Order, out of the ashes of the seminal Joy Division.  Are there any more counter examples?