Papert Koenig Lois, also known as PKL, was an advertising agency founded by Fred Papert, Julian Koenig and George Lois in January 1960. Its first office was in the Seagram Building in Park Avenue in Manhattan. Early clients included Peugeot and Xerox. Its campaigns were successful and it was the first agency to go public.
Examples of successful campaigns include Maypo porridge and Xerox. To reach older children, George Lois, took the existing slogan "I want my Maypo" and put it in the mouth of famous sportsmen like Mickey Mantle. To demonstrate the ease of use of a Xerox, it was shown being used by a little girl. When this was thought incredible, a chimpanzee was used instead to reinforce the point.
References
Papert Koenig Lois Wikipedia(Text) CC BY-SA