Dennis Callahan, 1937–2025, veteran and MIT software engineer

Dennis J. Callahan, of Waltham, died Wednesday, Oct. 8 2025 at Newton-Wellesley Hospital. He was 88.

Dennis was born on Mar. 29 1937 in Cambridge, a son of the late Dennis Joseph and Louise M. (Larson) Callahan, and was a graduate of Rindge Technical High School.

After high school he joined the U.S. Navy and served for four years during the Korean War.

Following his discharge from the service Dennis went to Newman Prep and Wentworth Institute, both in Boston, and Lowell Institute at MIT before embarking on a decades long career as a software engineer with MIT Lincoln Laboratory in Lexington.

A Waltham resident for more than fifty years, he and his wife, Marie, were longtime members of Our Lady’s Parish where Dennis was a member of the church choir. His love of music extended to his membership in the Mishawum Choral Society of Woburn.

For many years Dennis and Marie enjoyed winter vacations to Naples, Florida and summer trips to Ogunquit, Maine.

In addition to his wife of sixty-one years, Marie E. (Venesi) Callahan, he leaves his brother, Paul Callahan of Salem, New Hampshire; his sisters-in-law, Mildred Venesi of Washington, D.C., Barbara Sexton of Cambridge, and Anne Phillips of Tampa, Florida; and several nieces, nephews, and their families.

Dennis was also a brother of the late Ann Garabedian, Robert and Jeremiah Callahan, and Helen Edwards.

Family and friends will honor and remember Dennis’s life by gathering to visit beginning at 10 a.m. on Friday, Oct. 17 in Our Lady Comforter of the Afflicted Church, 880 Trapelo Road, Waltham, where his funeral mass will be celebrated at 11 a.m. Burial will be private.