Influential Music Acts, from my perspective (most important are mentioned first).
1. Django Reinhardt, for the reasons of influencing complete arts of guitar composition which many rock and metal acts (especially metal) took highly into their guitar construction.
2. Kraftwerk, for constructing electronic music which at the time was merely avant-garde music and forwarding it to a pop styling, which in turn would inspire a entire decade of electronic-influenced pop music: (the 1980s).
3. Muddy Waters / John Lee Hooker, for pioneering their respective fields of blues and taking it to the next direction which would in turn inspire the first rockabilly acts like Chuck Berry.
4. Pixies, for taking their unique style and inspiring many bands who directed a entire generation. Bands such as Modest Mouse, Nirvana, Radiohead, Superchunk and others cite the Pixies as inspiring them and all of these bands are (or will, except maybe Superchunk) inspiring others, as well.
5. Faith No More, for creating some of the most experimental music for hard rock at the time and pioneering even if they didn't want to a entire culture based off their (and Mr. Bungle's) style.
I only listed 5, but I'm sure the intelligent folks will create some additions that I will agree on. Heheheh. I'm surer we'll have some fair share of debates and arguments, too.