Nibbler
A disk copier that duplicates a floppy at the raw GCR level, letting it clone copy-protected disks that ordinary sector copiers choke on.
Ordinary copy programs read a floppy as decoded sectors and can only recreate that format. A nibbler instead reads the raw GCR "nibbles" before decoding and copies the track's exact bit pattern — including deliberately broken sectors, half-tracks and odd sync marks that made up the copy protection of the day. On the Commodore 64 and Apple II, the nibbler was therefore the tool that made protected games copyable.
The names were legendary: Fast Hack'em, Maverick and Burst Nibbler on the C64, often sped up with a parallel cable between computer and disk drive. Each new protection scheme spawned a new nibbler version — an arms race that ran until the floppy itself retired.