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John Thaddeus Brennan IV

June 25, 2019 | 19 comments

John Thaddeus Brennan IV, 57, of Onalaska, passed away as a result of a heart attack on June 23, 2019. John was born in Madison to John T. Brennan III and Patricia Yackley on February 20, 1962.  He married his best friend, Mary Becker, on October 4, 1986 in La Crosse.

John was a friendly man who could talk to anyone he just met like they had been friends for years.  He enjoyed being the life of the party and giving everyone memories, they would never forget.  He was a passionate golfer who believed if it wasn’t 18 holes, it wasn’t a true round of golf.  He loved playing on all the courses in the area but his favorite by far was Drugans.

He was a man who bled green and gold as the Green Bay Packers were his favorite football team.  He was happy to have witnessed their four Super Bowl wins. One of his favorite traditions was when he got to light the Santa head to kick-off the Christmas Season.

He loved his family with all his heart and they will forever miss his endless conversations.

He worked as an ultrasound technician until his retirement from the Tomah VA hospital in 2018.

John is survived by his wife, Mary; son, John T. (Amanda) Brennan V; daughter, Sara Brennan; parents, John T. (Gwen) Brennan III, Patricia (Karl) Prikry; step-mom, Judy Brennan; sisters, Joan McLaughlin, Jennifer Brennan and Giorgia Brennan; brother Jeff Brennan (special friend Emmy); and extended family and friends.

John was a loving husband, father, brother, uncle and friend.

John was preceded in death by his grandparents and his wife’s parents.

A special thank you to Gundersen Health System for their loving care and support and Coulee Region Cremation Group.

Hello everyone!! We have set a date for the celebration of life we will be hosting for our dad and husband. The celebration will be held at our home in Onalaska. We want to spend this time laughing with you all and remembering the fond memories we all share with our one of kind man, John. Our address is 4000 Mary Drive, Onalaska, WI 54650 

Food and drinks will be provided. You are welcome to bring your own items if you prefer, but please drink and have fun wisconsibly!

The celebration will begin at 1:00pm on August 31, 2019 and there will not be a set end time. Feel free to come and go as you please as the afternoon goes on. 

We look forward to the stories we know many of you have to share and being surrounded by the love we all so greatly appreciate from you all. 

We also encourage you to wear GREEN BAY PACKERS GEAR. GO PACK GO.



  1. Lois Zenke

    So sorry to hear of Johnny’s passing. Remember him as a fun, fun teenager.
    Our deepest sympathy to all.

    Old Friends,
    Duane and Lois Zenke

  2. Joann Germanson

    So sorry for your loss prayers to carry you through your old neighbor Lee &Joann Germanson

    • Jeff Zumach

      I have so very many memories of John that they swirl in my mind uncontrollably. John was more than a friend, he was a brother. John will always be in my heart and soul. Farewell old buddy, I’ll see you sometime down the road again. Deepest Sympathies and Condolences to family, because everyone was family to John!

  3. Wendy Berg-Hundt

    I went to high school with John, and since both of our last names were “B”, we often sat together in classes. He was always sweet to me and made me laugh every day! I was so sorry to hear of his passing and I know he will be missed. My sincere condolences to family and close friends.

    • Cathie & Forrest Moe

      So sorry to hear of his passing. Sending love and prayers to all.

  4. Brent Welch

    Marianne and I pass along our deepest sympathies. We are so sorry for your loss.

  5. kristine phillips

    Dr. Brennan and family,
    We are so very sorry for your loss. Our sincerest condolences and prayers go out to you.

    Sparta Campus Laboratory Staff

  6. Vickie

    I rode the bus with John on North Ridge. The bus always had to wait for him. LOL- but when he got on the bus he was always joking around. He made everyone laugh. Just thought I would share that memory with you. Blessing to his friends and family. Sorry for your loss.

  7. Susan Knowles

    Dear John & Gwen, So sorry to hear about the loss of your son. My thoughts , prayers and heartfelt sympathies are with you at this time. Susan Knowles

  8. Floyd Peterson

    Condolences John ,on the loss of your son, too young in the prime of life

    • Marilou & Floyd Peterson

      Dear John and Gwen, I am so shocked and saddened by this news. My sincere sympathies to you and your family. Blessings in the sad days ahead.

  9. Beth Moon

    Dear Mary & Family,
    So very sorry to hear of your loss. I never met John but know he had a very sweet and loving wife and children. Our sympathies and prayers to you all.

  10. Mary Pat Flanagan

    Oh John and Gwen. I am very sorry for your loss. Thoughts and Prayers.

  11. Rick Herbst

    I wish I could share a memory of John that you have not heard. Though I didn’t know John, I offer my deepest sympathy with heavy heart. I once found solace where I least expected it; I pray you can too.

    In my Father’s house are many rooms. If it were not so, would I have told you that I go to prepare a place for you?

    John 14:2

  12. Norma Steele

    Dr Brennan and family – Please know that our thoughts and prayers are with you. Sparta ER staff

  13. Brenda Hanson

    I went to high school with John as well! He was always easy going, cheerful, liked to laugh and make others laugh too! So sorry to hear about his passing. He was truly a blessing! My thoughts & prayers to John’s family.

  14. Lynn, Ross and Carmen

    Dear Gwen and John;
    We offer our most sincere condolences for the loss of your son. We know how it feels to lose a child and our hearts and prayers are with you during this sad time. Good memories will help ease the pain and keep the love alive.

  15. Donna Lodahl

    My sympathies to you. So sorry to hear of Johns passing.

  16. Vicky Miller Jessen

    My sympathy to his entire family. John was a very likable guy. I lived next door to him during high school and babysat Jeff several summers. Judy was a terrific mother to him and his siblings. God bless him. Hold the memories close to you now and forever.
    -Vicky Miller Jessen

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