What band spawned the most new bands?

Answer 1

Probably the Beatles. You hear almost every band post-beatles (and in fact during the Beatles height) saying how "the Beatles were a massive influence on me" from acts as divers as Black sabbath to Victoria justice (whose one of those awful Nickelodeon/Disney acts who my sister likes, so very, very different from the original metal band of Black Sabbath) say how they made them want to get into music.

Moreover, almost all metal acts owe something to Black Sabbath, which then leads back to the influence of the Beatles. this means that, to some extent, the Beatles invented metal. this can apply to most other genres of music post-Beatles, form Grunge to punk (which was actuly what influenced grunge, as well as metal) to progressive (or Prog) to whatever, they will say that so and so influence us, then so and so what influenced by so and so etc leading back to the Beatles

But you then Mr. I. LovetheBeatles, Who influenced the Beatles. Well this is a fine question and the answer is Elvis and Chuck Berry and most other famous 50s musical figures, maybe some 40's etc, So the actual answer to the question could be Elvis, but again who influenced Elvis. This Question will continue to knock on to the Likes of Mozart and Beethoven and then even older and eventually lead to some caveman who whacked a peace (i know I've put the wrong homophone for peace its just the doge spell check) of mammoth bone with some rock to create some form of basic noise

So there you have it, the "band" who spawned the most new bands was some caveman who whacked a peace of mammoth bone with some rock to create some form of basic noise.