Hermann Mejía started drawing very young, studying comics, including MAD Magazine, that had made their way to Venezuela from the United States, although he spoke no English at the time. He cites artists Sergio Aragonés (author of the wordless Groo the Wanderer strip) and Mort Drucker as favorites. He started collecting comics at age 13, and received his first artists' commission at 15, painting promotional graffiti for musical acts in Caracas. He studied at the Caracas Design Institute (Instituto de Diseño de Caracas), and from there went into commercial art, including the design of a series of Venezuelan postage stamps commemorating the Pope.
For coming in first in a sequential art contest, Mejía received a trip to New York City, where he met artist George Pratt, who had been one of the judges of the contest. Pratt took Mejía to the offices of DC Comics, and Mejía received work almost instantly. Through DC, Mejía met Charlie Kochman, the Licensed Publishing editor for both DC and MAD (which was by then a publication of DC Comics), and received an assignment for the April 1997 issue.
Mejía continued working for the New-York-based Mad while continuing to live in Venezuela for the next two years. In 1999 Mejía moved to the United States. He received a "Best in Magazine Feature" Reuben Award from the National Cartoonists Society in 2003.
Today, Mejía is continuing his work as a fine artist from his studio in Gowanus, Brooklyn, NY.