PC Paintbrush was a graphics editing software created by the ZSoft Corporation in 1984 for computers running the MS-DOS operating system.

Published alongside Microsoft Mouse DOS drivers version 4 from 1985 as a direct response to Mouse Systems bundling PCPaint with its mice, millions of copies were sold, and the program itself ended up licensed and used inside Windows 1.0, as Microsoft Paint; with an updated version licensed again for Windows 3.0, which (in an updated state) is still included in Windows today.

It was developed at a similar time to various bitmap paint programs for home computers such as PCPaint, which had been published in 1984 by Mouse Systems, who bundled it with their IBM PC mouses.

PC Paintbrush also competed with Apple Paint on the Apple II and MacPaint on Apple Computer's new Macintosh platform.

When PC Paintbrush was released in 1984, it had support for EGA.

PC Paintbrush was published as included software by Microsoft, with the early Microsoft Mouse, from version 4 of the DOS drivers in 1985. Both Microsoft and their competitor, Mouse Systems, bundled their mice with paint programs to drive sales.

Microsoft's mechanical mice outsold Mouse Systems' optical mice after a few years. Microsoft eventually bought the rights to use PC Paintbrush and incorporated it into Windows 1 in a cut-down edition, and bought the rights to a later more featured version of PC Paintbrush for Windows 3.

Along with the release of PC Paintbrush, ZSoft created the PCX image format, also used by Paint and Paintbrush in early Windows.