Dennis Siewert

Dennis “Boss” Siewert, 79, of Markesan, passed away Thursday, April 9, 2020 at Ripon Hospital. 

Dennis was born March 5,1941 in Fond du Lac the son of Herbert and Dorothy Ebert Siewert. He graduated from Markesan High School in 1959. After high school he worked at Alto Dairy, drove truck, and worked on the family farm. On March 29, 1963 he married the love of his life, Karen Horton, in Cambria, WI.

Dennis loved farming, and in 1970 he was able to purchase the family farm.  He really enjoyed tractor pulling, especially when he came in first. He loved watching old western movies, especially those with John Wayne or Walter Brennan.  He also enjoyed listening to old twangy country music. Dennis was never a dog person until Spunker “Dog” chose him as her human. From that point on the two were inseparable. Dennis was a long-time member of County Line Lutheran Church.  He was a very generous and giving man and will be
dearly missed by his family and friends.

Dennis is survived by his wife of 57 years, Karen Siewert; two daughters: Denise (Lora) Siewert of Minnesota, and Sheryl (Kelly) Immel of Fond du Lac; three grandchildren: Mathew and Sydney Immel, and Brooke Siewert; a great-grandchild, Evelyn; a brother, David (Joan) Siewert of Fox Lake; and two sisters: Janice (Gary) Streekstra of Waupun and Karen (Bob) Anderson of Randolph. He is also survived by many in-laws, nieces, nephews, and other family and friends. 

Dennis was preceded in death by his two sons: Jeff and Michael Siewert; and his parents: Herb and Dorothy Siewert.

Thank you to all the staff at Hospice Home of Hope that took such great care of Dennis and his family during this difficult time.

Due to the existing pandemic, a private burial will take place.  A celebration of life will be held at a later date for all family and friends.

Werner-Harmsen Funeral Home of Waupun and staff are serving the family.  Please visit our website at
for further information and to send condolences.