Board Thread:Questions and Answers/@comment-11255996-20130712192018/@comment-1038387-20130828140946

That's never explained by the powers that be, but it's in fandom discussions, it's usually ascribed to troublesome creator issues. Who created Wonder Girl?

Donna Troy was created by Bob Haney and Bruno Premiani. Cassie Sandsmark by John Byrne.

But the character "Wonder Girl" appeared earlier, created by Bob Kanigher. It was a teenage Diana. But Diana was created by William Moulton Marston, which would give him credit for the character (like Marv Wolfman "created" Nightwing, but he doesn't get creator credit for Dick Grayson).