Nintendo 64 accessories are first-party Nintendo hardware—and third-party hardware, licensed and unlicensed. Nintendo's first-party accessories are mainly transformative system expansions: the 64DD Internet multimedia platform, with a floppy drive, video capture and editor, game building setup, web browser, and online service; the controller plus its own expansions for storage and rumble feedback; and the RAM-boosting Expansion Pak for big improvements in graphics and gameplay. Third-party accessories include the essential game developer tools built by SGI and SN Systems on Nintendo's behalf, an unlicensed SharkWire online service, and unlicensed cheaper counterparts to first-party items. In the fifth generation of video game consoles, the Nintendo 64 had a market lifespan from 1996 to 2002.

The 64DD is a magnetic floppy disk drive peripheral for the Nintendo 64 game console developed by Nintendo. It was announced in 1995, prior to the Nintendo 64's 1996 launch, and after numerous delays was released in Japan on December 13, 1999. The "64" references both the Nintendo 64 console and the 64 MB storage capacity of the disks, and "DD" is short for "disk drive" or "dynamic drive".