Cyrix
Another company that manufactures 80x86 compatible CPUs, Cyrix is responsible for the MediaGX, 5x86, 6x86, 6x86MX, mII, and WinChip CPUs. They generally produce "entry level" CPUs, claiming high performance at low price, and this is generally true, except for FPU performance, which is far below the performance of genuine Intel CPUs. This renders the Cyrix family unsuitable for 3D uses, but acceptable for applications. Notably, and to Cyrix' credit, the 6x86 and later range have excellent MMUs.
Update: Cyrix is now owned by VIA