Kellar was born in Hagersville, Ontario, and played ringette as a child, before switching over to hockey. She competed for Team Ontario at the National Under 18 Championships in 1993. She led Team Ontario to the Gold Medal and was selected as the Most Valuable Player.[3] Kellar played with the Beatrice Aeros in 1998 and participated in the championship game of the Esso Nationals, netting an assist.[4]
She played for the Brown Bears women's ice hockey program at Brown University in Providence, Rhode Island from 1993 to 1997 and has an MBA from Wilfrid Laurier University.[5] While at Brown, she played second base on the softball team. She was a First Team All-Ivy League selection at softball in 1995 and 1997.[6] She was inducted into the Brown Athletics Hall of Fame in April 2005.[7]
She later played for the Burlington Barracudas of the Canadian Women's Hockey League. In the 2007–08 and 2008–09 seasons, she was voted the CWHL Top Defender and a CWHL Central All-Star. On September 14, 2010, Hockey Canada announced that Kellar, along with three other players retired from international hockey.[8]
Kellar is married and lives in Burlington, Ontario. She welcomed her first son, Owen, on October 22, 2004, and her second son, Zachary, on January 25, 2007.