LISA (Local Integrated System Architecture) was Apple's first personal computer and GUI -based operating system.
Both Apple's Steve Jobs and Microsoft's Bill Gates saw the first GUI-based OS, Xerox's Alto, released in 1979, and were inspired to bring GUI to the masses. Xerox released Star OS first, subsequently Apple released LISA in 1983 and Microsoft released Windows 1.0 in 1985.
The LISA OS was heralded by BYTE as "the most important development in computers in the last five years.” More than any short coming in the OS, LISA’s success was probably limited by its $9995 price tag. The LISA OS was included on a 5mhz Motorola 68000 CPU with a dual 5 1/4" floppy drive.
See a LISA 1 demo: