It occurs to me that Ditko, like Kirby, created an enormous amount of new series and characters.
As compared to, say, Neal Adams, another giant in the field. Adams worked almost exclusively on established characters like the Spectre, Deadman, Batman, X-Men, Avengers, Green Lantern/Green Arrow, Inhumans.
The one exception being Adams' Continuity characters in the 1980's that weren't particularly memorable, and echo the characters Adams worked on for DC in the late 1960's/early 1970's. Rather than creating new characters, Adams' innovation was more a refining of existing characters, and portraying them in a more "realistic" way. Or artwork more ornately detailed, if not more realistic. Adams' innovation was to create more of a visual style, that obviously many have imitated since.
Ditko also has a very distinct visual style. The splash pages on his pre-Marvel monster stories are very striking and atmospheric. Some of which I've thought of making enlarged copies of and framing. Along with Kirby he was an innovator with a lot of new ideas, characters, and series, but I think I love most his anthology stories.
And have a complete run of his stories in TALES OF SUSPENSE and TALES TO ASTONISH in Marvel Masterworks hardcovers. As well as tons more in 1970's reprints like WHERE CREATURES ROAM, WHERE MONSTERS DWELL, CREATURES ON THE LOOSE, MONSTERS ON THE PROWL, FEAR, and so forth.
