Keith Ian Giffen (born November 30, 1952) is an American comic book illustrator and writer.
His first published work was "The Sword and The Star", a black-and-white text story featured in Marvel Preview #4 (Jan. 1976), with writer Bill Mantlo. Giffen and Mantlo created Rocket Raccoon in Marvel Preview #7 (Summer 1976). Giffen is best known for his long runs illustrating and later writing the Legion of Super-Heroes title in the 1980s and 1990s. Giffen and writer Paul Levitz crafted "The Great Darkness Saga" in Legion of Super-Heroes vol. 2, #290–294 in 1982. In August 1984, a third volume of the Legion of Super-Heroes series was launched by Levitz and Giffen. Giffen plotted and pencilled the fourth volume of the Legion which began in November 1989.
In addition, Giffen co-created the humorous Justice League International series in 1987 with J. M. DeMatteis and Kevin Maguire. The success of that series led to a spinoff in 1989 titled Justice League Europe also co-written with DeMatteis and featuring art by Bart Sears. The Giffen/DeMatteis team worked on Justice League for five years and closed out their run with the "Breakdowns" storyline in 1991 and 1992. The two writers and Maguire reunited in 2003 for the Formerly Known as the Justice League miniseries and its 2005 sequel, "I Can't Believe It's Not the Justice League", published in JLA Classified.