The Grey is an endless route lacking color that is found in all known areas through the use of glitches, hacks, or exploits, and is considered one of Toontown's greatest mysteries. Toons that somehow make their way into the Grey can travel forever and never find anything. In some cases Toons enter the Grey unintentionally, and in others intentionally to ensure that a difficult task is done properly without failure.
- In Toontown Online, a few sections of streets had fences that could be walked through.
- Donald's Dock had one of those fences.
- In a Q&A livestream hosted by Slate on March 24, 2014, Sir Max confirmed that the Grey is canon to the storyline.
- Slappy once mentioned that the Grey is one of the many things that bewilders him and wonders what secrets it holds.
- On the Toontown Rewritten website, Professor Prepostera made a blog post introducing his research about the Grey. In a later blog post, he described it as an unnatural place and an outstanding creative approach, yet pesky, way to bypass security in Cog facilities.
- If a Toon jumps while traveling in the Grey, they will jump and then hover in mid-air in a jumping pose (but still able to walk normally) until they come into contact with a surface again.
- The sky or background related to the respective area from where the Toon is located can still be seen in the Grey.
- The spelling "grey" (as opposed to "gray") comes from British English, but they mean the same thing.
- In Estate houses, the grey is green, but when toons open their Shticker Books it turns grey.