The Z80 is a CPU designed to be binary compatible with 8080 while featuring improvements that enabled a system designer to build a system with a lot fewer external components. The company behind the Z80 was Zilog, founded by ex intel employee Federico Faggin and Ralph Ungermann at the end of 1974.

More details can be found here.

Computers in my collection based on Z80 are:

Luxor ABC 80
Luxor ABC 800
Sinclair ZX81