His death took place on day before a show of his Fire Island watercolors was to open at ClampArt in Chelsea. The opening will go on as planned.
Mr. de Michiell designed the poster for many Broadway shows, including recent revivals of La Cage aux Folles and A Little Night Music. His illustration typically featured stylized rendering of characters in the plays or musicals which somewhere between cartoon and caricature, and often incorporated elements of Cubism, albeit rendered in a light-hearted vein.
He also designed the posters for many editions of the Broadway Cares/Equity Fights AIDS fundraisers Gypsy of the Year, Broadway Flea Market and Easter Bonnet competition.
Robert de Michiell's illustrations were also seen regularly in Entertainment Weekly and the New Yorker, as well as the Wall Street Journal, Reader's Digest and Time.
He was born to Nan C. DeMichiell and Robert L. DeMichiell, and later came to use a different spelling of the family surname. He was a graduate of the Rhode Island School of Design. He was married to Jeffrey Michael Wilson, a theatrical general manager, who survives him.