A Mass of Christian Burial for James “Jim” Joseph Brennan, Jr. of Watertown will be celebrated on Saturday, Feb. 7, 2026, at 11 a.m. at Sacred Heart of Jesus Parish, 39 Sixth Street, East Cambridge.
Jim was born in Willimantic, Connecticut, to the late James Joseph Brennan, Sr. and Donna Marie (Smith) Brennan. He passed away unexpectedly on Jan. 26, 2026, at the age of 63.
Jim grew up in Silver Spring, Maryland with his parents and four siblings. He graduated from Northwood High in 1980 and earned one of his many advanced degrees at the University of Maryland College Park, among several other institutions. Jim and his wife, Lisa, relocated toNew England and have lived in Watertown with their four children for the past 30 years.
Jim’s career included work as an Information Systems Architect, Senior Programmer Analyst, Director of Systems Management, and overall computer wizard who started his own business. His work brought him, literally, all the way around the globe. After a career shift to education in the early 2000s, he dedicated the rest of his life to teaching and education, including his work for The Sacred Heart Of Jesus Parish religious education program.
Jim was passionate, exceedingly generous, and wicked smart. He raised his family to be the same. Jim was dedicated to learning and encouraging everyone to explore their passions with unlimited enthusiasm. Whether you knew him as James, Jim, Jimmy, Jimbo, or Mr. Jim his legacy is one of kindness, love, faith, and never underestimating the importance of a homecooked meal, which always included brownies.
Jim is survived by his wife Lisa (Marenghi) Brennan; his son Jimmy Brennan, daughter-in-law Darcie Brennan, and their daughter Raylee Mae Toops; his son Tommy Brennan; his son Noah Brennan; his daughter Jill Holbert and son-in-law Steve Holbert; and his son-by-proxy Dylan Fraser. He is also survived by his sisters Jean, Shawn, and Linda, his brother Thomas, brothers- in-law Dave and Jeff.
Though dearly missed, we take comfort knowing that Jim is now reunited with his parents, in- laws, and beloved dog, Ginger.
Visiting hours will be held on Friday, Feb. 6, 2026, from 4 to 8 p.m. at MacDonald, Rockwell & MacDonald Funeral Home, 270 Main St., Watertown. Relatives and friends are kindly invited to attend.
In lieu of flowers, donations in Jim’s memory may be made to Donors Choose to help students and their classrooms all over. For in memoriam donations, after selecting a project (or choosing to let Donors Choose select a project for you) simply select “dedicate this donation” before you check out.