Apart from his distinguished career as a painter, Ellis left an indelible mark on the art world in both southern California and northern New Mexico.
According to art writer MaLin Wilson-Powell in her essay "Bob Ellis: Navigating Portals of Perception, from Aegean Temples to Woodcuts, 2004 - 2011", the trajectory of Ellis's professional career began with his All-American Midwestern roots, "opening day at the Cleveland Indians, nickel ice cream cones, the Cleveland Museum's Classical and Medieval Armor Court and their free Saturday classes .
In Mexico, Ellis produced paintings influenced by the figurative tradition of such artists as Diego Rivera, José Clemente Orozco, and David Alfaro Siqueiros.
It was during this time at the commercial print shop owned by theosophist Henry Geiger that Ellis developed a love of small presses, typesetting, and cut-and-past layout, influences that would recur in his artwork throughout his career.
The years of Ellis's leadership at the Harwood were notable for a major museum expansion completed in 1997, including the addition of the world renown Agnes Martin Gallery.
According to an interview in a review of the retrospective, Louise Lewis, professor emeritus of art history at California State University at Northridge, says: “The counterpoint between minimalist and detailed, painted and photographed elements of the image — subtle at first glance and then quite overt — stimulates the viewer to resolve these visual incongruencies.” The review goes on to quote Ellis himself about the next development in his career, the San Cristóbal paintings, done during the 1980s.
In 2006 he began his "Post-Aegean" series (2006-2010) that breaks free from references to the marble columns of Greek architecture and focuses instead on the relationship of the formal elements of the composition within the rectangular canvass.
Towards the end of his life, Ellis would come full circle and had returned to the carousel theme in an unfinished piece he was working on at the time of his death.
He was responsible for the acquisition of a collection of seven paintings by the pre-eminent contemporary American artist, Agnes Martin, a longtime Taos resident and Ellis's close friend, and oversaw the construction of the gallery where they are on permanent display.
Today, the Agnes Martin Gallery attracts visitors from all over the world and has helped put the Harwood Museum on the map as a major contemporary art destination in New Mexico, on par with The Lightning Field, 1997, the environment installation by artist Walter De Maria.
[8] After the opening of the renovated museum and Agnes Martin Gallery, Ellis embarked on one final push to affirm the place of the Taos art colony in the development of American modernism.
Ten years in the making, by which time Ellis had retired from the museum and joined the Mandelman-Ribak Foundation board, an agreement was reached between the parties.