In the Golden Age, it was seldom necessary to give criminals a motivation. They were just crooks, simple as that. Some of them (Luthor notably) also were mad scientists, a bogeyman familiar to youngsters from the TV and radio serials.
But as the Silver Age wore on, establishing a motive for the criminal behavior became more important. Two of the oddest motivations came from Captain Cold and Sonar.
Captain Cold was one of the Silver Age Flash's first villains, appearing in Showcase #8, the second comic to feature the Scarlet Speedster. His weapon was a gun that could freeze things instantly; a rather pedestrian power. But he was an interesting character nonetheless because his reason for pursuing a life of crime was to impress women.
Initially he had a crush on Iris West, Barry Allen's girlfriend, but would later transfer his affections to other women. Along the way, he picked up a supervillain polar opposite named Heat Wave, who frequently was his rival for the affections of women.
Sonar, on the other hand, had the ability to control sounds with a special tuning fork. Again, this is not an ability likely to fascinate readers for long. But Sonar's back story was wild. He came from a small European country named Modora. Frustrated that his homeland was not a player on the world stage, he resolved to make it a major power.
In one of the annoying coincidences that plagued Green Lantern in the early years (see for example, my earlier post about Qward), GL discovers Sonar because he is searching for a stamp from Modora. He searches the mind of an old clockmaker, whose apprentice, Bito Wladon (Sonar) has just quit the job. The clockmaker is worried because Wladon had discussed his dangerous ideas before leaving.
GL battles Sonar twice, but each time the villain manages to escape. The third time turns out to be a charm and in gratitude, the citizens of Modora issue a special stamp for Green Lantern to give to Pie-Face.