Snap! Crackle! and Pop! are the embodiment of Rice Krispies cereal. They were born in 1928 when artist Vernon Grant was inspired by a Rice Krispies radio jingle describing how the puffed grains "merrily snap, crackle and pop in a bowl of milk," so he drew the three elves and sent them off to Kellogg's ad agency of record. But for a few short years in the 1950s, there was a fourth elf. A space elf! His name? Pow! If not for the Internet, Pow! would be lost to time. He appeared in two TV commercials. "Pow means power and power's nice! Rice Krispies power from whole grain rice!” said the announcer... "Now Pow doesn't say much...he just goes ahead and does things...like putting power into every...lightweight spoonful of Kellogg's Rice Krispies!"
Smithsonian has the full story: "The Untold Tale of Pow!, the Fourth Rice Krispies Elf."