1952 - Semifinals vs. Montreal
Boston rallied from a 2-0 deficit to take a lead in the series, only to fall in OT in the sixth game. In the tiebreaking matchup, an injured and woozy Maurice Richard scored the game-winner to eliminate the 4th-seeded Bruins. The game is immortalized in an iconic photograph of a bloodied (and probably concussed) Richard shaking hands with black-eyed Boston goalie "Sugar" Jim Henry.
1959 - Semifinals vs. Toronto
The Bruins had been to the Finals in consecutive seasons, and that experience played a role as they quickly jumped out to a 2-0 lead in the series. Leading 3-2 late in the third game, they surrendered a goal in the final minutes to Leafs sniper Gerry Ehman, and then saw Ehman score the OT winner to get the Leafs back in the series. The Bruins lost control of the series, falling behind 3-2 before forcing a 7th game. It was none other than Ehman who scored the series-winner with minutes to go in the final period.
1971 - Quarterfinals vs. Montreal
In the heyday of the Orr/Espo dynasty, the Bruins had dominated the regular season and looked well on their way to a second Cup. After winning the opening match, they took a 5-1 lead in Game 2, only to improbably allow 6 consecutive goals in a stunning loss. Boston regrouped to win the next two games, but Montreal closed out the series with consecutive victories. Rookie goaltender Ken Dryden played a key role in the upset.
1979 - Semifinals vs. Montreal
In perhaps the most heartbreaking loss of all, Don Cherry's Bruins looked to have finally solved the Habs in the 7th game. Rick Middleton scored with 4 minutes to play, breaking a 3-3 tie. In one of the most notorious moments in team history, the Bruins were called for too many men on the ice with less than two minutes to go; Guy Lafleur tied the game with a goal on the subsequent power play. Yvon Lambert scored the OT winner to send the Habs to the Finals, where they beat the Rangers.
1982 - Conference finals vs. Quebec
After a first-round sweet, the Bruins dominated the first two games and looked to be headed to a showdown with the dynastic Islander. The Nords, who had previously upset the rival Habs, spoiled the celebration by reeling off 3 consecutive wins to take control of the series. Boston forced a 7th game with an OT winner, but lost the final match 2-1 in the Nords' second straight stunning upset.
2004 - Conference quarterfinals vs. Montreal
The division-champion Bruins again jumped out to a 3-1 lead in the series, but were steamrolled in games 5 and 6. The final game was scoreless after 50 minutes, with highly-touted (ha!) goalies Andrew Raycroft and Jose Theodore exchanging saves. Montreal's Richard Zednik broke the tie and added an empty-netter for a 2-0 victory, sending Raycroft and star center Joe Thornton down a path of notoriety from which they have yet to recover.
2009 - Conference semifinals vs. Carolina
The heavily-favored Bruins, top-seeded in the East and fresh off a sweep of the hated Canadiens, ran headlong into a red-hot Carolina team. The Hurricanes reeled off 3 straight wins to push Boston to the brink, but the Bruins recovered with two dominant efforts to force the tiebreaking Game 7. After 78 minutes of intense end-to-end action, Carolina's Scott Walker scored to eliminate the Bruins.