Obituary of Guillermo Mancillas

Guillermo “Memo” Mancillas, born 5/6/1955 passed on 5/14/2026 at 71 years old. 

Guillermo was born in Chihuahua, Mexico and spent the last twenty years living in Webster, NY after spending time in Texas, Colorado, and Italy. 

He is survived by his wife, Georgina, his children Guillermo (Melissa), Marcela (Bryan), and Alejandro (Alicia), as well as his grandchildren Edan, Christopher, and Alexander, and his siblings Rafael, Ana Luisa and Eduardo. He is predeceased by his parents Rafael and Trinidad. 

Memo completed his bachelor’s degree in mechanical engineering at Tecnologico de Chihuahua and master’s degree in business administration at Sul Ross State University and built an admirable and prolific career with time at Ford and John Deere, before making a long-lasting impact at MKS Instruments. While at MKS he fulfilled simultaneous leadership roles on three continents and yielded an impressive track record of success that he was celebrated by his company and employees. He was an avid golfer and craftsman, never shying away from a challenge or opportunity to learn and expand his skills. 

His genuine selflessness, generosity, and heart expanded his nuclear family to include countless friends and led to the unofficial adoption of many of his children’s friends, many of whom continue to count themselves among his children to this day. Always giving of his time, his resources, and his skills, he never hesitated to provide what was his to give. He is adored by his grandchildren and thrived in their energy, spirit, and sense of humor; he was ceaselessly proud to watch them grow. 

Memo was a devoted servant of Christ, offering guidance and advice of others’ growth into the church whenever appropriate, but understood that our journeys are our own to walk. After retirement he gladly gave his extra time and energy to support the Knights of Columbus and the Focus Pregnancy Center to expand his relationship and impact of the church. Guillermo exemplified leadership, commitment, honor, honesty, and a tireless devotion to his family and church. His impact was worldwide and he will be missed and honored by the expansive family he nurtured and loved. 

Family and friends may call at Paul W. Harris Funeral Home, 570 Kings Hwy So., Thursday, May 21, 2026 from 4:00 PM – 7:00 PM. The Funeral will be held at Holy Trinity Church, 1460 Ridge Rd, Webster, Friday, May 22, 2026 at 10:30 AM. Interment to immediately follow at White Haven Memorial Park.

Con Guillermo oramos:  En paz me acostaré y asimismo dormiré, porque solo tú, Señor, me haces vivir confiado.