John Brockman is known in the Monkees world as the 'head' used in the initial promotional campaign for The Monkees' 1968 feature film, Head. You can read a detailed analysis of the Brockman campaign at SOTCAA.
Peter Tork and Davy Jones held up a poster of Brockman during a late 1968 appearance on the Hy Lit Show in Philadelphia, Pennsylvania:
Here's a roadside billboard advertising Head and featuring Brockman, located in Hollywood on the corner of Sunset Boulevard and Crescent Heights (presumably photographed in late 1968):
Today Brockman works as a literary agent and author, and is employed by Michael Nesmith. In 1996 Brockman launched Edge, a website "devoted to discussions of cutting edge science by many of the world's brilliant thinkers." The following biography of Brockman can be found on the site:
John Brockman is a cultural impresario whose career has encompassed the avant-garde art world, science, books, software, and the Internet. In the 1960s he coined the word "intermedia" and pioneered "intermedia kinetic environments" in art, theatre, and commerce, while also consulting for clients such as General Electric, Columbia Pictures, Scott Paper, The Pentagon, and the White House.
In 1973, he formed Brockman, Inc., the international literary and software agency specializing in serious nonfiction. He is the founder of the nonprofit Edge Foundation, Inc. and editor of Edge, the highly acclaimed website devoted to discussions of cutting edge science by many of the world's brilliant thinkers, the leaders of what he has termed "the third culture."
In 1997, Brockman made a cameo appearance in The Monkees' ABC television special that year:
Brockman plays a lawyer and can be seen 25 seconds into the show:
The November/December 2010 issue of Shindig! featured an updated take of Brockman's Head promotional imagery: