The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples were delivered in March 1976, and it was officially introduced on the market in July 1976. With the revenue from the Z80, the company built its own chip factories and grew to over a thousand employees over the following two years.

The Zilog Z80 is a software-compatible extension and enhancement of the Intel 8080 and, like it, was mainly aimed at embedded systems. Although used in that role, the Z80 also became one of the most widely used CPUs in desktop computers and home computers from the 1970s to the mid-1980s. It was also common in military applications, musical equipment such as synthesizers (like the Roland Jupiter-8), and coin-operated arcade games of the late 1970s and early 1980s, including Pac-Man.

Zilog licensed the Z80 to the US-based Synertek and Mostek, which had helped them with initial production, as well as to a European second-source manufacturer SGS. The design was also copied by several Japanese, East European and Soviet manufacturers. This won the Z80 acceptance in the world market since large companies like NEC, Toshiba, Sharp, and Hitachi started to manufacture the device (or their own Z80-compatible clones or designs).

In recent decades Zilog has refocused on the ever-growing market for embedded systems, and the most recent Z80-compatible microcontroller family, the fully pipelined 24-bit eZ80 with a linear 16 MB address range, has been successfully introduced alongside the simpler Z80 and Z180 products.