Sean Patrick O'Sullivan

Sean Patrick O’Sullivan, age 60, of Acton, Massachusetts, passed away on December 28th. He was born on August 25th, 1965, in Niskayuna, NY, to his parents Joe and Joan. He was raised in Clifton Park, NY, along with his four siblings. His father was an avid bird watcher, so the O’Sullivan’s spent much time hiking and camping in the Adirondack’s where Sean grew an appreciation for nature. Sean excelled in youth swimming, baseball, and basketball, and was an exceptional student.

Sean attended Shenendehowa Central High School and graduated in 1983. He had the first in-game dunk in the school’s history. In his senior year, Sean received the UNCAS Award, an honor given to the top athletes at Shenendehowa, recognizing exceptional performance and dedication. He then went to Princeton University to study Chemical Engineering. While at Princeton, Sean was a member of The Cottage Club and enjoyed playing basketball. He was a proud alumnus who loved to go to reunions and games with his kids. He would often be captured in pictures over the years wearing his favorite Princeton basketball polo.

He graduated in 1987 and spent the next 20 years working at Colgate-Palmolive in Morristown, NJ, Kansas City, KS, and NYC, NY. His expertise was in areas such as Manufacturing and Supply Chain Planning. He was particularly proud of his patent on a method for dispensing toothpaste. In 2001, he went back to school while working for Colgate-Palmolive to get his MBA at Cornell. He had two children while working and attending graduate school, and graduated with his MBA in 2003. He and Deanne had two more children, and, in 2007, they moved the family to Acton, MA, to work at Welch’s.

Sean met Deanne at Colgate when she replaced him in his own role, working on an SAP implementation. They flirted over exchanging a computer and then dated while he lived in Kansas and she lived in New Jersey. They traveled extensively, with trips often involving golf, which was his passion. After just a few years of knowing each other, they knew they were a match - they shared the same beliefs on raising a family (both wanting a large one), a strong love for family, and the same passions for adventure. After getting married, they spent 3 weeks exploring Australia and dreaming about their future together.

He will be remembered for his notably dry sense of humor and admiration of nature, but most importantly, his love for family. Sean loved history, finance, and watching his kids grow up. In constant support of his kids’ dreams and aspirations, he played an active role in their youth teams and education. He taught them lessons ranging from fixing the car and lawn mower to explaining parabolas to his fourth grader (True story!). His own passion for learning was relentless. After retiring, he spent time tutoring math and could often be found watching YouTube lectures on quantum physics and machine learning. He instilled that same passion in his children through his example and encouragement, especially during his careful whiteboard lessons over homework problems. He was a devoted spouse, brother, father and friend, and loved playing and watching sports, reading, watching historical documentaries, and leading bible studies at St. Elizabeth of Hungary church.

Sean spent 15 years bravely fighting Inclusion Body Myositis. There were a lot of things this disease took away from him. In facing this loss, he remained relentlessly insistent that he was “blessed”. He never allowed those around him to forget how much he loved them and how lucky he felt to live the life he did despite all its challenges.

He is preceded in death by his parents, Joe and Joan O’Sullivan of Clifton Park, NY. He is survived by his wife Deanne and their children Caitlin, Sarah, Aidan, and Grace, and his siblings Aileen McCarthy, Christine O’Sullivan, Patricia O’Sullivan, and Brendan O’Sullivan.

Visitation:

Thursday, Jan. 1st, 2026

4-7 PM

Badger Funeral Home 347 King Street Littleton, MA 01460

Funeral Mass:

Friday, Jan. 2nd, 2026

10:00-11:00 AM

St. Elizabeth of Hungary 89 Arlington St. Acton, MA 01720

Burial Following the Funeral Mass.

In lieu of flowers, we welcome you to donate to the Myositis Association at https://www.myositis.org/get-involved/ways-give/ and please insert the following email address so the family can thank you personally: deannewos@gmail.com 

Arrangements are under the care of Badger Funeral Home, A Life Celebration Home, 347 King St., Littleton, MA, 01460. 978-486-3709