Sean O'Reilly, 43, of Chicago, transitioned peacefully and surrounded by love on February 26, 2021.

Sean was born on January 6 in Oak Lawn to Francie (Hynes) and John O'Reilly both of Co. Mayo, Ireland. He grew up in Tinley Park with his two sisters, Deirdre and Mary. Sean was a 1996 graduate of Marian Catholic High School.  He graduated Magna Cum Laude from Marquette University in 2000. He doubled majored in History and Criminology Law Studies. Sean worked for the Federal Government for 20 years. He served as a Supervisory Officer within the Department of Homeland Security since 2011 - working with a team whom he loved in a position he truly enjoyed. He was fondly called the "zen master" by his colleagues.

Sean's most important role was spouse to Shannon (Harrity) and father to son Eamon and twin girls Madelyn and Vivian. Sean loved playing soccer with Eamon and taking the girls on long walks. Sean was an excellent dad.  He was patient, loving and fun.  His favorite part of the day was during bedtime routine with Eamon, when they prayed and talked about the day's events.

Sean enjoyed getting to know people. He was an excellent listener who loved to chat.  Sean had a way of making people feel comfortable and at ease no matter the situation.  He had a quick wit and curious mind. He enjoyed a good craic, pushing buttons and encouraging critical thinking on any topic but mostly politics. He found relaxation and peace in a good cup of coffee while writing.  He often took long runs along the lake and worked his schedule around Marquette men's basketball.  Each year, he looked forward to March Madness with optimism and had his heart broken each tournament. In most years, he would then focus his attention on his wife's Jayhawks.  He lived life one day at time.

Sean was a man of deep faith. He served as a Eucharistic minister at Old St. Mary's, and previously served as a member of the parish council.

He was a kind man who touched so many lives.  He was met in eternal life by his mother Frances.  He is survived by his spouse, Shannon Harrity; three children, Eamon (seven), twins Vivian and Madelyn (two); father John O'Reilly of Tinley Park; sister Deirdre of Mokena; sister Mary (Bienias) and Bryan of Tinley Park; friend Deric Jordan (Kimberly) of Chicago;  nieces and nephews: Bennett Harrity of Overland Park, KS, Frannie and Joe Bienias of Tinley Park, and Ellie Jean and Ethan of Lee's Summit, MO; many loving in-laws including: Bryan Harrity, Amanda Witty, Jaime Harrity, Derek and Laura Harrity, Kyle and Cassie Harrity, Nancy Harrity, James and Charlotte Harrity, and Laura Harrity in Kansas and Missouri. He leaves behind a host of aunts, uncles and cousins in Ireland and in the States, family of his heart and countless friends.

Sean, as he did most weeks, would want to thank and acknowledge those working in the Cancer Center and all of his care team at Northwestern. The kindness, stories, care and friendship given to him over the years meant so much to him.

Peace.

Visitation Thursday March 4, 2021 at 9:30 a.m. until the time of the 10:15 a.m. Funeral Mass at Old St. Mary's Church, 1500 S. Michigan Ave., Chicago, IL 60605. Please RSVP at the following link for those attending in-person https://www.signupgenius.com/go/409094baaa828a7f85-34funeral . All in attendance will be required to wear facemasks and adhere to all local COVID requirements. The Funeral Mass will be livestreamed at www.oldstmarys.com . Interment Good Shepherd Cemetery, Orland Park, IL. A celebration of life will take place when it is more safe.

In lieu of flowers, anyone who wishes to honor Sean may choose to make a contribution to the Sean O'Reilly Family Trust. Please mail checks to the Sean O'Reilly Family Trust c/o Michalik Funeral Home, 1056 West Chicago Avenue, Chicago, Illinois 60642.

For further information please call 312-421-0936.