John Mark McGill, A.K.A “Mad Dog”, 60, of Onset, passed away at home on July 20th, 2021. He was the son of the late Barbra McGill and Thomas McGill. John is the youngest of six children. He was predeceased by his siblings, Thomas McGill, Kathy McGill, Robert McGill. He is survived by brothers Joseph McGill and Timothy McGill. In addition to his brothers, he leaves behind three children, James Servidori, his wife Jessica Servidori, Jessica Adamson, her husband Robert Adamson and Patrick McGill, his wife Julia McGill and their four children, Jayden, Abel, Bellamy and Maisie. A Graveside service will be held at 11:00 am on Friday, August 20th at Mosswood Cemetery in Cotuit. All family and friends are welcome.