Johnny thunder 

Fall 1940

March 1941

Originally called Johnny Thunderbolt, the story of a not-very-bright young man gifted with a magic thunderbolt began in Flash Comics in .January 1940.

The Thunderbolt was controlled by the magic word "Cei U", but Johnny didn't know that, and could only say it by accident.  (Say, you'd think they'd clue a fellow in, wouldn't you.).

The feature became Johnny Thunder in Flash 11, November 1940.

By All Star 2, Johnny had picked up a girl friend Daisy Darling (first app Flash #2) but the Thunderbolt was still just a magic lightning bolt. 

By All Star 3, Winter 1940-41, the Thunderbolt has started to exhibit a more humanized form. 

In Flash 15, March 1941, Thunderbolt has started to talk. 

By Summer 1941, Thunderbolt  assumed his classic appearance, but he has not yet settled on a standard color. From World's Finest #2 By All Star 6, August 1941. The Thunderbolt has turned a proper shade of pink.
In Flash 20, August 1941, Johnny finally figures out what the magic word is, which makes him a much stronger force for good, (as long as he remembers it.) from World's Finest 3 Fall 41
In Flash 21 Sept 1941, Johnny adopts Peachy Pet, who gradually replaces Daisy Darling as the main supporting character..

In Flash 42 June 1943 Johnny and the Thunderbolt return 
to Bahdnesia and the Thunderbolt's family is introduced.
Shocko is the Thunderbolt's son. He first appears in Flash 69.