This patch for GoldenEye will unlock:

All Solo Levels

All Multi Characters

All Multi Levels

All Cheats Available

Created with the GoldenEye Setup Editor.

Update:

Added a second, simpler patch derived from the gameshark code.
This one only unlocks all singleplayer & multiplayer levels.
But it's lightweight and should works with most other mods!
It changes offset C5B45 from 8C 42 6F B4 to 34 02 00 01.

Apply to "GoldenEye 007 (U) [!].z64" (Big Endian):

  CRC-32: b6330846
     MD5: 70c525880240c1e838b8b1be35666c3b
   SHA-1: abe01e4aeb033b6c0836819f549c791b26cfde83
 SHA-256: 2cdcec8a9f0cb6e36337f3ee39d8ad105dc8afa6ba1c02d466e8f5b771f9a162

Special thanks to Carnivorous