William Theodore Mattison, Jr., age 85, of Anderson, SC, passed away on Monday, May 11, 2026, at Rainey Hospice House.

Born October 5, 1940, in Greenville, SC, he was the son of the late William Theodore Mattison, Sr. and Alice Virginia Sherard Mattison. He was also preceded in death by his brother, Mark Mattison A. Mattisson, Sr.; brother-in-law, Lewis B. Haynie, Sr.; and nephew, David P. Haynie.

Theo was a graduate of Boys High and went on to graduate from Davidson College. He received his medical degree at the University of South Carolina. He did his internship and internal medicine residency at Emory University Affiliated Hospitals. He served in the United States Naval Reserves for 2 years, one of which was with the United States Marine Corps in Vietnam. He practiced internal medicine in Atlanta for 10 years and worked at the Greenville Mental Health Centers for 23 years.

Theo was an avid supporter of humanitarian causes, the preservation of wildlife, and the conservation of the environment. He was a member of First Presbyterian Church of Anderson.

He is survived by his sister, Alice Sherard “Sherry” M. Haynie; sister-in-law, Rebecca M. Mattison; and seven incredibly wonderful nieces and nephews, their spouses and children.

A private service will be held. 

In lieu of flowers, memorial contributions may be made to Hospice of the Upstate, 1835 Rogers Rd., Anderson, SC 29621, Anderson Interfaith Ministries (AIM), 1202 S Murray Ave, Anderson, SC 29624, Calvary Home for Children, 110 Calvary Home Circle, Anderson, SC 29621, or a charity of one’s choice.

Condolences may be left for the family by visiting WWW.MCDOUGALDFUNERALHOME.COM