For me it was coming from William Messner-Loebs in a three part story beginning in The Flash , Grodd's first appearance in several years, and Loebs took the opportunities presented by this gap, and the massive shift in the status-quo and tonal shift of both the book and the times, to re-present him as a very credible threat indeed. A literal apex predator. Messner-Loebs wasn't adverse to revisiting Barry Allen's old rogues, but most were presented as belonging to that generation, and Gorilla Grodd was the first (bar arguably Vandal Savage) to be presented as a still valid and major force. Amoral, superior, and very much now, more than ever, The Flash's most dangerous foe... this three parter was, and still is, a great story to read.
William Messner-Loebs isn't all that well remembered today, and that is a great shame as his long run on The Flash is one of the underrated gems of the late 1980s, and should be celebrated for its fine work in developing Wally West and his learning to be The Flash. A socially concsious writer Messner-Loebs work still stands to rereading as his stories were usually about something...
Very powerful villain, as was strong as a super ape, smart as Lex, and Tp like Prof X!