Professor Pepperwinkle
aka Professor Jasper J. Pepperwinkle
A "well-known" inventor and apparent acquantaince of both Clark Kent and Superman who resides in a "modest suburban home" near Metropolis.
In December 1974, Professor Pepperwinkle comes out of retirement to construct his "greatest invention," the "sonic-boom-boomer" a device which can "simulate a boom equivalent to a speeding SST breaking the sound barrier," for people who don't live near airports but will now be able to enjoy a boom whever the mood hits them. Superman discovers Pepperwinkle's small laboratory in a building in Metropolis which supports the bizarre device on its roof (Act No. 442/1, Dec 1974: "The Midnight Murder Show!").
In March 1976, Professor Pepperwinkle provides Clark Kent with an anti-gravity "gizmo" that the intrepid reporter, who is now temporarily without his super-powers as the result of a complex scheme instigated by the alien observer Mr. Xavier, uses to defeat a group of Inter-Gang hoodlums (S No. 297: "Clark Kent Forever--Superman Never!").
Professor Pepperwinkle considers himself to be the "greatest inventor in the world," while Clark Kent notes that he has "been known to fowl-up occasionally" (S No. 297, Mar 1976: "Clark Kent Forever--Superman Never!").
(This entry still needs biographic info from S No. 289/1, Jul 1975: "The Phantom Horseman of Metropolis!"; S No. 308, Feb 1977: "This Planet is Mine!")