Barney Guillermo Williams (born March 13, 1977) is a Canadian rower who won a gold medal at the 2003 world championships in Milan and a silver in the same event at the 2004 Summer Olympics.

On April 18, 2021, Barney resigned from his position as head coach of the University of Victoria's women's varsity rowing program following 3 seasons in response to Rowing Canada ruling that he had contravened an aspect of the National Coaching Certification Program code of ethics in the fall of 2018 .

He was sanctioned with the appointment of a mentor coach or a 12-month ban from Rowing Canada activities on April 20, 2021.

[2] Born in the Argentine city of San Martín de los Andes, Williams was educated at Upper Canada College, the University of Victoria and then at Jesus College, University of Oxford where he was President of the Oxford University Boat Club.

[3] He is married to the Canadian rower Buffy-Lynne Williams, who won bronze in the women's eight at the 2000 Summer Olympics in Sydney Australia, and placed fourth in the women's pair at the 2004 Summer Olympics in Athens Greece.