Re:
Dia-compe
Shimano/Suntour/SRAM (counts as two)
Giant
Mountain Bike
Dia-compe had their hand in everything, made the first rockshox, aheadsets, and people rebranded many of their parts.
The big three Groupset companies, without them, and all three, thing would not have kept evolving and buying ideas from others and commercialising them.
Giant pioneered and brought to market many things, even if they are just Giant.
Trek are probably up there with them in that respect.
Mountain Bike, well just because...
Many others can go on there
Araya, if you ever look at their bike catalogues, they have every style bike you will have seen back in the day, pioneers of commercial Aluminium bikes too.
Mavic, brought 'The Wheel' as a whole to be a thing for MTBs, but we're getting out of retro or near enough.