Margaret (Maggie) Anne Sumner (née O’Neill) of Greenwich, Conn., died on Feb. 20, 2026, after a courageous battle with cancer.
She is survived by her mother, Anne O’Neill of New Rochelle; and siblings, Jeannie Loferski (Michael Loferski), Catherine McWilliam (James McWilliam), Sheila O’Neill (Kerry Metz), Tricia O’Neill (Nick Mulford), and Timothy O’Neill (Krystin O’Neill).
She is predeceased by her father, John T. O’Neill, and nephew Henry “Hank” McWilliam, both of Rye.
Maggie was a devoted daughter, sister, and aunt to Sophia Baskin (Brett Baskin), Peter Loferski, Charlie Metz, Cate McWilliam, Maddy and Julia and Anna O’Neill. She was a great aunt to Beau Baskin.
Born in Rye and a proud New Yorker, Maggie was known for her love of dance, art, food, travel, dogs, and yoga. She danced professionally with Harkness Ballet and was a teacher at the Rye Ballet Conservatory. While she considered herself a perpetual yoga student, she was also a gifted yoga teacher.
Small in stature, Maggie will always be remembered for her impeccable style, sweet tooth, quick wit, and big attitude.
“Though she may be but little, she is fierce.” – William Shakespeare
A Memorial Mass will be held at 10 a.m. Thursday, March 5, 2026, at Church of the Resurrection. In lieu of flowers, Maggie requested donations to the FDNY Foundation.
