The NEC PC-9801 (or the PC-98 for short) is a Japanese microcomputer manufactured by NEC. It first appeared in 1982, and employed an 8086 CPU. It ran at a clock speed of 5 MHz, with two µPD7220 display controllers (one for text, the other for video graphics), and shipped with 128 KB of RAM, expandable to 640 KB. Its 8-color display had a maximum resolution of 640×400 pixels. Its successor, the PC-9801E, which appeared in 1983, employed an 8086-2 CPU, which could selectably run at a speed of either 5 or 8 MHz.

In the 1980s and early 1990's, NEC dominated the Japan domestic PC market with more than 60% of the PCs sold as PC9801 or PC8801. In 1990, IBM Japan introduced the DOS/V OS which enabled to display Japanese text on ordinary IBM PC/AT's VGA adapter. After that, the fall and decline of the PC98 began. The PC-9801's last successor was the Celeron-based PC-9821Ra43 (with a clockspeed 433MHz), which appeared in 2000.

FreeBSD/pc98 runs on PC-9801s equipped with an i386 or compatible.

Software for the PC98 generally ran from program and data disks (Disk 0 & 1) or (A & B), and NEC did not have a strong GUI to go up against Microsoft's Windows 95 when it took Japan's PC market by storm. NEC's decision to work with Microsoft to offer a PC98 compatible version of Windows 95 could be seen as the first step towards the 9800 series computer's downfall, as consumers were no longer required to have an NEC-built system to run software designed for Windows.

The PC98 is different from the IBM PC in many ways; for instance, it uses its own 16 bit C-Bus instead of the ISA bus; BIOS, I/O port addressing, memory management and graphics output are also different. However, localized MS-DOS or Windows will still run on PC-9801s.

Seiko Epson manufactured PC-9801 clones, as well as compatible peripherals.