Those who aren't familiar with his name would probably know his work by sight. I will quote from the biographical section of the Kelly Freas Gallery site:
Frank Kelly Freas's artwork has graced the covers of hundreds of science fiction books and magazines, including works by Poul Anderson, Isaac Asimov, Arthur C. Clarke, Robert Heinlein, Dean R. Koontz, Ursula K. LeGuin, Frederik Pohl, and A. E. Van Vogt. He has contributed covers to Mad Magazine, illustrated the jacket for Queen's best-selling album News of The World, and created the cover of the 1992 Star Trek Annual. An official NASA artist, Freas' space posters hang in the Smithsonian Museum in Washington. He was also commissioned by the Skylab I astronauts to design their crew patch.
Dubbed the "most popular sf artist in the history of the field" by the respected Encyclopedia of Science Fiction, Freas is the first artist to have won 10 Hugo Awards, having been nominated an all-time record of 20 times. He has also won numerous other genre awards, including the 1991 NATTS Hall of Fame. In 1994, Starlog magazine included him in their prestigious list of The 200 Most Important People in Science Fiction and Fantasy.
Frank Kelly Freas, Rest in Peace.