The Energon Pub

[MYoung23]

was there ever a crossover between the two franchises either in comic or cartoon form?

There have been several GI Joe/Transformers crossovers in the comics. You can google them.

During Season 3 of G-1 Cobra Commander appears in the episode "Only Human" going by the name of "Old Snake." Clips of that can be found on youtube.

[Duke of Luns]

In the cartoons, there have been no direct crossovers(save for the afformentioned Season 3 episode "Only Human"), but there have been a few references:

In the G.I. Joe episode "The Gamesmaster", at the begining their are small robots fighting each other. They somewhat resemble Optimus Prime and Shockwave:











"Dinobot Island" was technically created over in G.I. Joe, in the episode "Primordial Plot". This episode had Cobra Commander doing a Jurrassic Park and cloning a small army of Dinosaur's, or something to that extent. The animation models look surprisingly similar too:





In the TF Season 3 episode "The Big Broadcast of 2006", there was a show called "Space Age Jack", and one of the characters announed loudly "Yoooo Jack!!!"

In another Season 3 episode, "Dweller in the Depths", Wreck Gar shouts "Yooo Joe!".

Last but certainly not least(that I know of, or can think of right now), there's the revlation that Marrissa Fairborne is Flint's daughter! A "hologram" of Flint appeared in the TF Season 3 episode "The Killing Jar", and he had the same voice actor as Flint from Joe. According to the TF Wiki, Flint Dille, the writer/story editor for Transformers, did indeed for this to be a reference/crossover.

[TechnoSeeds]

In the original comics run of GI Joe, there were crossovers early in the series and then another one around issue 140 (I think 155 was the last issue). One time, I bought the first crossover in the GI Joe comic series as a book. It just combined all the issues and made it a paperback. The second crossover had Cobra Commander and Megatron making a deal.

I've also enjoyed reading the new crossovers in the comics over the last few years.