The Transfer Pak is a device for the Nintendo 64 that allows the transfer of data between the system and a Game Boy or Game Boy Color cartridge. The Transfer Pak has a Game Boy Color slot and a part that fits onto the expansion port of the N64 controller. It is considered the predecessor of the GameCube-Game Boy Advance cable.

The Transfer Pak was included with the game Pokémon Stadium, as the game's main feature was importing Pokémon teams from Game Boy titles. Pokémon Stadium also included a "GB Tower" mode for playing Pokémon Red, Blue, and Yellow on the N64 via a built-in Game Boy emulator (which included unlockable "Doduo" and "Dodrio" modes which would speed up the game's processor by 2 and 3, respectively).

It was originally planned that Perfect Dark was going to be able to link up with the Game Boy Camera and map faces shot from the camera to characters in Perfect Dark. This feature was scrapped, due to technical issues. Instead, when the Game Boy version of Perfect Dark is linked to the N64 version via the Transfer Pak, you'll unlock a Cloaking Device for use at anytime, an R-Tracker to hunt down any hidden weapons in a level, Hurricane Fists that allow for superpowered punching, and the ever popular All Guns cheat, giving you access to all guns in the game, and even doubles of one handed guns and all classic weapons.

Normally it is not possible to actually play Game Boy games on the N64 with the Transfer Pak, as was possible with the Super Game Boy on the Super Nintendo Entertainment System. However, Pokémon Stadium and Pokémon Stadium 2 allowed the compatible Pokémon titles to be played in the Game Boy Tower.