In Adventure #267, Saturn Girl re-captures a 20th century crook who has stolen a gun from the detective who had taken him into custody by making the gun appear to him as a cobra.

This fellow has the honor of being the first genine villain ever depicted in Legion lore.

What about the villain responsible for the "Secret Of The Quintile Crystal", EDE?

and then there is the tale of Lucifer 7 in the SECRETS OF THE LSH mini-series...or arent these considered canonical lore any more?

Those stories weren't published until years later!

That crook needs a name! Mr. Green, because of his bright green suit?

We know he's a criminal because he's the only man not wearing a tie.

In the Adventure 247, the first page (in the Archives) shows the three legionnaires attacking a "criminal getaway rocket" - but the incident isn't followed up in the story and we don't see any actual criminals.

It would be interesting to catalogue the Legion missions and see how many were rescuing people from disasters and how many were capturing criminals/villains.