Theophil A. Groell was born February 11, 1932, in Pittsburgh, Pennsylvania, the son of Joseph P. and Helen (Drewes) Groell. He began his career as a painter after graduating in 1953 from Carnegie Institute of Technology [now Carnegie Mellon University] with a Bachelor of Fine Arts degree. In New York City he exhibited early work under the name of Theophil Repke at Tanager Gallery and in Clement Greenberg's Emerging Talent exhibition at Kootz Gallery. Of his Tanager exhibition Dore Ashton in the New York Times noted (December 5, 1956), “Repke is a careful and subtle painter whose insistence on the human figure has been fruitful.”

His paintings and drawings of the figure, still life, and landscape were featured in many one-man exhibitions, including at Green Mountain Gallery and Tatistcheff Gallery in New York City and Frost Gully Gallery in Portland, Maine, as well as in group invitational shows, including the American Academy of Arts & Letters, and touring exhibitions such as Contemporary American Realism Since 1960 (The Pennsylvania Academy of Fine Arts, 1981). His drawings also appeared in books such as A Guide to Drawing (Mendelowitz and Wakeham, Fifth Edition) and Realism Today (National Academy of Design). Shortly before his death he completed a visual essay on his fifty-year painting career, Working from Life, which awaits publication.

He began spending summers in Deer Isle, Maine while he was teaching art in New York City. Following his early retirement in 1987, after teaching for twenty-eight years, he divided his residence between Hydra, Greece, and Deer Isle, painting outdoors from April through November each year. He was a regular exhibitor at Penobscot Bay area galleries, including Turtle Gallery, Deer Isle, and was a member of the Deer Isle Artists Association for many years.

Known to family, friends, and in the communities where he lived as Ted or Theo, he was known also for his vigorous political activism on behalf of peace and justice issues. He died March 4, 2004, in Bangor, Maine, survived by his longtime fiancée, Joan Weaver, of Hydra, Greece, and Stonington, Maine; a son, Paul Groell, and his wife, Catherine, of Fairfield, Connecticut; Paul's mother, Mary Ann Strugar, of Deer Isle, Maine; a brother, Joseph W. Groell, and his wife, Marjorie, of New York City; a granddaughter, Olivia; and a niece, Anne.

In May 2004 his Greek landscape paintings were exhibited in Hydra, Greece. A retrospective show in Maine of his paintings and drawings is planned to follow publication of his book.