Dark Justin Puppy is friends with Nega Dennis (the evil clone of Dennis).
Dark Justin looks a lot like the original Justin Puppy, except he has purple fur with a dark shade of purple on his belly, red slit-shaped eyes, yellow sclera, red nose, and a light blue forked tongue. He also has slightly thicker eyebrows and dark eyelids.
Much like Dark Rayman, Dark Justin takes the role of an antagonistic shadow. Dark Justin first appears in the ToonWorld video games (except the spinoffs) where, if he touched Justin Puppy, he could kill him instantly. However, he could be defeated by reaching the exit portal before him, causing him to collapse.
- Dark Justin Puppy is one of the few villains who are evil clones of cartoon heroes.
- As shown in some episodes of the ToonWorld series, Dark Justin Puppy is occasionally shown alongside the E.V.I.L Troop, possibly hinting that he could be a member of the group.
- Dark Justin Puppy makes a brief cameo in ToonWorld All-Stars: The Movie during the climactic fight scene, where he can be seen fighting alongside Nega Dennis and Dark R1 Rayman/Raymesis Jr.