Mary Ann O’Callaghan, 77, of Madison, Wisconsin, passed away unexpectedly on November 4, 2026, surrounded by her family. Born on April 29, 1949, in Milwaukee, Mary Ann was the oldest of five children born to Anthony and Florence (Becker) Klink.

Mary Ann grew up in Milwaukee. She graduated as valedictorian of her class at Holy Angels Academy before attending Marquette University, where she earned a degree in biology in 1970. She later went back to school to earn an additional degree in accounting. Mary Ann worked in the laboratory at Red Star Yeast and later as a classroom aide for the Brownsburg, Indiana, school district.

On December 26, 1970, Mary Ann married Stephen O’Callaghan in Milwaukee. Together, they created a loving home for their six children wherever life took them, raising their family in communities across the Midwest, including Wisconsin, Minnesota, Illinois, and Indiana.

Mary Ann was an avid reader and possessed a lifelong love of learning. She especially loved mystery novels, puzzles, numbers, history and architectural design. Mary Ann possessed the intelligence and ability to excel at whatever she set her mind to, and she could have pursued almost any path in life. We are so blessed that she chose to devote so much of her time, energy, and remarkable gifts to the life she shared with her family. She instilled in her six children the values she lived by every day: honesty, integrity, respect, and compassion. Those values, and the lessons she passed on, will live on through her children and grandchildren.

She is survived by her husband, Steve; her six children, Patrick (Kira) O’Callaghan, Peg (Matt) Sheaffer, Dan (Beth) O’Callaghan, Michael (Alyssa) Ryanjoy, Brian (Kat) O’Callaghan, and Erin (Josh Worden) O’Callaghan; her siblings, Robert (Pat) Klink, Patricia (Patrick) O’Connell, Joanne Klink, and Kathleen (Tom) Borowski; and her grandchildren, Avery, Abby, Olivia, Laurel, Ruby, Ian, Milena, Sadie, Mickey, Cora, Winnie, Clara, Jimmy, and Thea.

A Mass of Christian Burial will take place at St. Peter Catholic Church, 5001 N Sherman Ave, Madison, WI on Tuesday, November 10, 2026, at 11 a.m. A visitation will take place at the church from 9:30 a.m. until the time of service. Mary Ann will be laid to rest at Resurrection Cemetery in Madison.

In lieu of flowers, the family asks that donations be made in Mary Ann’s name to the Madison Public Library Foundation, Luke House, or Midwest Environmental Advocates.

To view her obituary and leave a memory, please visit: www.ryanfuneralservice.com

Ryan Funeral Home & Cremation Services
2418 N. Sherman Avenue
608-249-8257

Mary Ann O'Callaghan

April 29, 1949 - November 04, 2026

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