Pitching the Spider against one costumed lunatic was never going to be enough for Jerry Siegel, and the number surely reached its' zenith in "The Spider versus the Sinister Seven". The number of superpowered crooks swelled to the level usually associated with American comics. As well as the Sinister Seven themselves, there was also their heroic counterpart, the Society of Heroes, with whom the Spider briefly allied, and most of whom met with a sticky end, years before this sort of thing became in vogue with comics. And that's not mentioning the [Laughing?] Hyena and Crab-Man, two no-mark costumed crooks the Spider tussles with early on.

At a massive 31 instalments, possibly all five pages long, this was by far the longest Spider serial. I only have the second installment, and even those aren't my scans. They were taken from a filesharing network, where the original scanner (credit and respect to him for doing what IPC seem incapable of) has worked wonders with what looks like a very badly damaged Lion issue. More thorough overviews of both the Sinister Seven and the Society of Heroes can be read at the excellent International Hero, here and here respectively.