Marissa O'Neil was named head coach of the Polar Bears in the summer of 2010. In her first year at the helm in 2010-11, she piloted a resurgance for the Polar Bears that included a 15-8-2 record, giving Bowdoin its winningest campaign since 2007. In 2012-13 season O'Neil lead the Polar Bears to their best finish since 2004, defeating Middlebury for the NESCAC Championship, hosting the first women's ice hockey NCAA Tournament game at Watson Arena and ending the season 21-5-2. As a result, O'Neil earned NESCAC Coach of the Year honors.
A 2005 graduate of Bowdoin, O’Neil enjoyed prior stints within the the New England Small College Athletic Conference, serving as an assistant ice hockey and field hockey coach at Amherst in 2008 and '09 and as head women's ice hockey coach at Williams in 2010. During her time with the Lord Jeffs, the team finished 44-9-4, won one NESCAC title (2008) and one NCAA Championship (2009). She enjoyed a fantastic season at the helm of the Ephs, leading the squad to a 12-11-2 record and fourth-place finish in the conference, up from 8-16-1 the year prior to her arrival.
O’Neil was a two-sport standout while a student at Bowdoin. In 2005, she received the Lucy L. Shulman Award, given to Bowdoin’s most outstanding female athlete. A three-time All-NESCAC honoree in ice hockey, she was named to the 2003 NCAA Division III All-Tournament team. In field hockey, she was the NESCAC Rookie of the Year in 2001, the NESCAC Player of the Year in 2003, a three-time First Team All-NESCAC selection and a First Team All-American. O'Neil was inducted in the Bowdoin Athletics Hall of Honor in the fall of 2018.
On the ice, O'Neil helped Bowdoin win a pair of NESCAC Championships and earn four NCAA Tournament appearances as a player.
Following her graduation from Bowdoin, O’Neil spent one year as an assistant ice and field hockey coach at Saint Anselm’s College. Her following year was spent as an assistant athletic director at Middlesex School. O'Neil graduated from Bowdoin with a bachelor's degree in Sociology and owns a master's degree in sports management from UMass-Amherst.