Prior to the current issues of Gargoyles, Greg has also written the following comics:
- Captain Atom (1986-1991): Greg wrote 16 issues and co-wrote 33 along with Cary Bates (who also worked on Gargoyles and W.I.T.C.H.).
- An 11-page story featuring the "Justice League Europe". Was a crossover parody with Gargoyles, and featured many injokes for the series. The story was published in JLA Showcase #1 and cover dated February 2000.
- The second story in The Amazing Spider-Man #622 titled "Stages of Grief". The issue was released Februrary 24, 2010.