Dennett Grover's father was a prominent lawyer, and his mother was a cultured woman who especially fostered her son's early predilection for art. When he was about eleven years old, his father brought Alden Finney Brooks into their home to paint portraits of the family, giving the boy an opportunity to watch an artist work. The family moved to Chicago in 1875, and two years later Grover entered the University of Chicago. On Saturdays he attended art classes at the Chicago Academy of Design (the forerunner of the School of the Art Institute of Chicago). Eventually, his progress in art persuaded him, and his family, that he should quit his pre-law studies. In August 1879 he went to Munich to study at the Royal Academy.
There he formed a close friendship with another aspiring young painter, Julius Rolshoven of Detroit. The two also associated with the group of students devoted to Frank Duveneck. During their first free summer they traveled together through Europe and, on reaching Venice, fell in with the "Duveneck Boys." At the end of the season Grover and Rolshoven went to Florence and Duveneck's school there instead of returning to Munich. When Duveneck gave up the school in 1882, Grover and Rolshoven remained and set up one of their own, the Mugnone School of Art. Within two years, however, Grover had moved to Paris to extend his studies at the Académie Julian, where he worked under Gustav Boulanger and Jean-Paul Laurens. In 1886 he made his first showing in an Academy annual exhibition; however, his work was not included in an annual again until 1905. Thereafter, he was represented sporadically in annuals through 1927.
Grover and Rolshoven returned to America in 1887, and in that year Grover and Rolshoven's sister Louise were married. The couple settled in Chicago, and he accepted a teaching position at the School of the Art Institute of Chicago. In 1891 he was on the team of artists who worked under H. H. Gross to paint a cyclorama representing the Great Chicago Fire of 1871. This experience doubtless led him, in early 1892, to become a partner in Ernest Albert and Walter Burridge's theatrical set-designing and painting firm. Its promotional literature described Grover as "known throughout the entire art world as an academician and figure painter of high rank-a strong draughtsman and colorist." The firm did a considerable amount of business for the World's Columbian Exposition of 1893. Among its notable productions there was a "Volcano of Kilauea," which, by aid of magic-lantern slides, spouted flames and lava. Despite the high promise and hyperbole of its advertising, Albert, Grover and Burridge, Scenic and Decorative Painters went bankrupt within two years.
Meanwhile, Grover had attained his initial fine-arts honor in 1892, winning the first Yerkes Prize awarded by the Art Institute of Chicago. He gave up his Art Institute teaching post that year and began a local career as a painter of portraits, views of Venice, and, later, of Glacier and Yellowstone national parks. He also executed mural decorations that brought him increasing distinction.
By the end of the 1930s it could be said that Grover, along with Ralph Clarkson and Lorado Taft, had dominated the Chicago art world for the first quarter of the twentieth century-and that the trio embodied conservatism, with Grover the most militant in its defense. As he frequently chaired the juries for the Art Institute's annual exhibitions, he became the focus in 1922 of a battle over jury structure and practice initiated by the younger, more progressive Chicago artists. The outcome was a schism in the Chicago Society of Artists (of which Grover had at one time been president), with the conservative members breaking away to form the Association of Chicago Painters and Sculptors. Grover served as its first president.
Among the many other organizations to which Grover belonged were the National Society of Mural Painters and the Society of Western Artists, of which he was president from 1906 to 1908. His talent for the monumental, early demonstrated in cyclorama and scene painting, was amply exercised in the many murals he produced. Prominent among them were decorations for the Branford (Conn.) Memorial Library, (1897); Holy Angels Cathedral, Chicago; Blackstone Memorial Library, Chicago (1903); and the First National Bank, Chicago.