Suellen Rocca, a founding member of the short-lived but influential 1960s Chicago art group the Hairy Who and a fiercely original artist whose hieroglyphic, phantasmagoric work poked a finger in the eye of late-20th-century modernist purities, died on March 26 at a hospice in Naperville, Ill., a suburb of Chicago. She was 76.

Matthew Marks Gallery in New York, which represents her, said the cause was pancreatic cancer.

At a time when the deadpan consumer imagery of Pop Art was giving way to the restraint of Minimalism and Conceptualism, Ms. Rocca and five former classmates from the School of the Art Institute of Chicago came together under the sway of influences as disparate as Dubuffet, Native American art, hand-painted store signs, the Sears catalog and the natural-history displays at the Field Museum to create a rambunctious form of painting and sculpture that tacked hard against prevailing orthodoxies.

“There is about many of these works a relentlessly gabby, arm-twisting, eyeball-contacting quality that comes as a great surprise in a gallery that we associate with the spare statements of Agnes Martin and Brice Marden,” John Russell wrote in The New York Times in a review of a 1982 Pace Gallery show. He added: “Why are they so repulsive? Are they all equally repulsive? Are we wrong not to like them? These are fair questions, and they deserve an answer.”

Eventually the answer was that their unorthodox ethos, ignored by many East and West Coast critics as a regionalist aberration, came to be embraced by younger generations, who saw themselves reflected in its exuberance, irreverence and vernacular American overload.