Ratchet and Clank are the main protagonists of the Ratchet & Clank series. Created by Insomniac Games, the characters have made cameos in the Jak and Daxter series, and have appeared in other games alongside Jak and Daxter. Likewise, Jak and Daxter have made similar cameos in Ratchet & Clank games.
The frequency of cross-appearances is the result of Naughty Dog and Insomniac Games' close relationship throughout their history. Dating back to their development of Crash Bandicoot and Spyro the Dragon, respectively, the two studios shared both technology and an overlapping fanbase. Homages to, references to, and cameos within the two series followed, as well as a non-canon cross-over game, PlayStation Move Heroes. Furthermore, Ratchet and Clank served as story rivals to Jak and Daxter in the game PlayStation All-Stars Battle Royale.
In Jak 3, Ratchet and Clank appear as civilian targets in separate Ratchet and Clank gun courses (as well as Tyhrranoids, an enemy race from Up Your Arsenal, appearing as enemy targets). The duo returns in Jak X: Combat Racing, with Ratchet appearing as an unlockable racer with his own description, and Clank appearing on a pennant for purchase from the secrets shop for 40,000 Precursor orbs. To unlock Ratchet in the PS2 version, a save file from Ratchet: Deadlocked must be present on the memory card. In the PS4 version, a save file from Ratchet & Clank (2016 game) must be present on the system.
Collectible masks resembling Ratchet and Clank appear in Daxter, the former found in the transit system during the mission "Take care of bugs in transit system", and the latter found in the first tanker mission, "Collect 30 gems from the tanker".
Lastly, Daxter references Clank in the Jak and Daxter Trilogy movie, saying, "As you can see, Jak and I can easily take out any robot that boots up. Even cute talking ones that like to 'clank' around! Yeah, that's right! I said it!"