Education
After being drafted Brennan chose to go to college and played at Boston University for 4 years.
After being drafted Brennan chose to go to college and played at Boston University for 4 years.
He played briefly in the National Hockey League with a number of teams including the Colorado Avalanche, San Jose Sharks, New York Rangers, Los Angeles Kings, Nashville Predators, and Boston Bruins. Brennan was chosen in the 3rd round, 46th overall by the Quebec Nordiques in the 1991 National Hockey League Entry Draft out of high school. In 1992 he played in the World Junior Ice Hockey Championship for the United States.
Brennan"s most successful collegiate season came during his junior year (1993–1994) when he scored 35 points in 41 games and earned a number of honors including Hockey East First All-Star team honors and National Collegiate Athletic Association East Second All-American team honors.
After college Brennan joined the Cornwall Aces for the 1995-1996 season. Brennan spent the 1996-1997 season with the Hershey Bears in addition to making his National Hockey League debut, appearing in 2 games with the Colorado Avalanche.
Brennan then signed as a free agent with the San Jose Sharks in 1997. He spent the majority of the 1997-1998 season with the Sharks minor league affiliate Kentucky Thoroughblades while also appearing in 11 games with the Sharks before being traded to the New York Rangers and finishing the season with the Hartford Wolf Pack.
The 1998-1999 season saw Brennan play 47 games with the Wolf Pack in addition to playing in an National Hockey League career high 24 games with the Rangers.
Brennan played the next 2 seasons with the Lowell Lock Monsters. During the 2000-2001 season Brennan also managed to play in 2 games with the Los Angeles Kings. In 2001 Brennan signed with the Nashville Predators and spent the majority of the 2001–2002 season in the minors, only appearing in 4 games with the Predators.
The 2002-2003 and 2003-2004 seasons saw Brennan play with the Providence Bruins.
During the 2002–2003 season he played in 7 games with the Boston Bruins, his last stint in the National Hockey League to date. Brennan has played in Europe since 2004.
He split one year between Swiss team South Carolina Bern of the National Lawyers Association before transferring to Augsburger Panther of the DEL in Germany. Brennan remained in Germany the following season and played 3 seasons with the Nürnberg Ice Tigers.
Brennan then spent the 2008-2009 season in the Austrian Hockey League with The Human Context TWK Innsbruck before retiring.