An eye for Mongombo.
I was looking for information online about the sadly-incompleted Fantagraphics mini-series Eye of Mongombo (the only thing I found of significance, beyond sale listings, was a mention halfway down the page in an outdated comic FAQ), and I found this page listing comic book characters that physically transform into either animals or the opposite sex. It’s just part of a larger site that catalogs such examples of shapeshifting in books, movies, paintings, etc. Keep in mind the elaborate list of notations as you peruse the entries.
God bless the internet.