One of only five men to win all four Grand Slams, Agassi called it a career after losing in the third round of last year's U.S. Open. He won eight Grand Slam titles and 52 other tournaments and, in 2003, became the oldest man to be ranked No. 1 in the world.
2 of 30Lou Capozzola/SI
Mario Lemieux, 40
One of the greatest players in NHL history, Super Mario retired last January for the second time, citing an irregular heartbeat and recognition that the new, faster NHL had left him behind. The six-time scoring champion and first-ballot Hall of Fame inductee in 1997 won two Stanley Cups and two Conn Smythe Trophies with the Penguins, the team he bought in 1999 to rescue it from bankruptcy.
3 of 30AP
Paul Tagliabue, 65
The man who succeeded Pete Rozelle as NFL Commissioner in 1989 stepped down after a highly successful tenure during which the league achieved labor peace and massive revenue growth while establishing itself as America's most popular and envied pro sport.
4 of 30Simon Bruty/SI
Zinedine Zidane, 34
It's unfortunate that many will cite Zidane's head-butt in the final match of the 2006 World Cup as one of the most memorable moments of his career, because the three-time World Footballer of the Year deserves better. One of the greatest soccer players ever, Zidane led France to the 1998 World Cup title and the 2000 European Championship, dazzling millions with his fundamentals and artistry on the pitch.
5 of 30Clive Rose/Getty Images
Michael Schumacher's condition is improving according to wife
6 of 30Heinz Kluetmeier/SI
Doug Flutie, 43
His 48-yard Hail Mary pass to defeat Miami as time expired is one of the most memorable plays in college football history. Frequently told he was too small to succeed as a pro, the 5' 10", 180-pound 1984 Heisman-winner played 12 seasons in the NFL and eight in the CFL, where he was a six-time MVP and winner of three Grey Cup championships.
7 of 30Bob Martin/SI
Lindsay Davenport, 30
Though she's loathe to use the word retire, the three-time grand slam tournament-winner confirms that she doesn't envision rejoining the tour after she gives birth to her first child next year. If so, those who watched her at last year's U.S. Open had the honor of seeing Davenport's final tournament.
8 of 30John Biever/SI
Jerome Bettis, 34
The Bus went out on top, calling it quits after the Steelers prevailed in Super Bowl XL, which was played in his hometown of Detroit. Bettis ended his 13 seasons as the fifth all-time leading rusher in NFL history (13,662 yards).
9 of 30AP
Eddie Sutton, 70
Before his retirement in May, he was considered the best active basketball coach to have never won a national title. Sutton was the first coach to take four schools to the NCAA Tournament (Creighton, Arkansas, Kentucky and Oklahoma State). Only four coaches have more than the 798 wins Sutton amassed in his 36-year career: Dean Smith (879), Adolph Rupp (876), Bob Knight (869 entering the 2006-07 season), and Jim Phelan (830).
10 of 30AP
Ian Thorpe, 24
One of the greatest swimmers of all time, Thorpedo said at a news conference in November that he suddenly realized there's more to life than his sport. The Australian superstar won nine Olympic medals (five gold, three silver, one bronze), and broke 13 world records.
11 of 30John Iacono/SI
Dick Vermeil, 69
A head coach for 15 years with three NFL teams, Vermeil wore his emotions on his sleeve and was as passionate about the game as any man who walked the sidelines. He led the St. Louis Rams to a heart-stopping victory over the Titans in Super Bowl XXXIV.
12 of 30David E. Klutho/SI
Steve Yzerman, 41
One of the most popular sports figures in Detroit, the man known simply as the Captain helped restore the downtrodden Red Wings to glory by winning three Stanley Cups during his 23-year career with the team. Yzerman scored 1,755 points, the sixth most in NHL history, and won an Olympic gold medal with Canada in 2002.
13 of 30Al Tielemans/SI
Deion Sanders, 38
The Baltimore Ravens brought him out of retirement in 2004, hoping he could help them win a Super Bowl as a fifth defensive back, but it never happened. Prime Time was a lot less flamboyant in his second go-round, but the best shutdown corner in the history of the NFL is a sure-fire Hall of Famer.
14 of 30Manny Millan/SI
Martina Navratilova, 49
This time she says it's for real. Navratilova first retired in 1994, having won 167 singles titles, including six consecutive at Wimbledon. She returned for doubles competition in 2000 and stayed on top of her game until the very end, winning the mixed doubles championship at the U.S. Open in her final pro match.
15 of 30Al Tielemans/SI
Curtis Martin, 33
The only thing missing is the "official" retirement announcement, but there's little doubt the 11-year veteran has played his last game in the NFL. Martin and Barry Sanders are the only players to begin their careers with 10 consecutive 1,000-yard seasons. Martin retires as the Jets all-time leading rusher (10,302 yards) and is fourth on the NFL's all-time rushing list (14,101).
16 of 30Chuck Solomon/SI
Jeff Bagwell, 38
The 1994 NL MVP, four-time All Star and 1991 NL Rookie of the Year hit 449 home runs in his 15 seasons, all of them with the Astros. He owns club records for RBIs (1,529), walks (1,401) and extra-base hits (969).
17 of 30AP
John Chaney, 74
A father figure to those he coached -- and a hot-tempered terror to those who opposed him -- the two-time National Coach of the Year took Temple to 17 NCAA Tournaments and five regional finals during his 24 seasons with the Temple Owls.
18 of 30Al Tielemans/SI
Jimmy Smith, 37
A precise route-runner who overcame a series of injuries and substance abuse problems, Smith ranked seventh all-time in the NFL in receptions (862) and 11th in receiving yards (12, 287) when he announced his retirement in May.
19 of 30AP
The three-year-old colt's bid for the Triple Crown was cut short in gruesome, heartbreaking fashion when he suffered a life-threatening injury -- breaking three bones above and below his right rear ankle -- at the start of the Preakness Stakes. Most horses are put down in such situations, but Barbaro's owners spared nothing to nurse him back to health and he is on the verge of leaving the hospital after seven months.
20 of 30Bob Rosato/SI
Billy Tubbs, 71
One of the most colorful characters to ever coach men's college basketball, Tubbs compiled a 641-340 record over 31 seasons, and won more games at Oklahoma (333) than any other hoops coach in Sooners' history. The two-time National Coach of the Year also paced the sidelines at Southwestern, Texas Christian and, most recently, Lamar, where he continues to serve as athletic director.
21 of 30Damian Strohmeyer/SI
Tie Domi, 36
One of the last of a dying breed of enforcers, the right-winger played 16 seasons for the Rangers, Jets and, most notably, his beloved Maple Leafs, leaving his knuckle marks on the league and leaving as its fourth all-time leader in penalty minutes (3,515).
22 of 30AP
Willie Roaf, 36
The 11-time All-Pro was chosen by Pro Football Hall of Fame voters as the starting left tackle for the 1990s All-Decade Team. Roaf had a stellar career with the New Orleans Saints and Kansas City Chiefs.
23 of 30Jamie Squire/Getty Images
Terry Labonte, 50
The 1984 and 1996 NASCAR points champion scaled back his schedule two years ago and finally made the last start of his 29-year career in November in his native Texas. The Ice Man -- or Texas Terry -- as he was called, made 848 starts and won 22 races.
24 of 30Darren McNamara/Getty Images
Dawn Staley, 36
The five-time WNBA All-Star guard (No. 5) finished her career with 2,226 points, 1,337 assists and 537 rebounds over six-plus seasons. She also was a fixture on the U.S. Olympic teams, winning gold medals at Atlanta, Sydney and Athens. She was chosen as the U.S. flagbearer in Greece.
25 of 30Otto Greule Jr/Getty Images
Fisher DeBerry, 68
Among active coaches, only Joe Paterno (41 years at Penn State) and Bobby Bowden (31 years at Florida State) had a longer tenure at a school than DeBerry, who retired in December as the winningest coach in Air Force history. In 23 seasons he compiled a 169-107-1 record and went 35-11 against Army and Navy.
26 of 30Lou Capozzola/SI
Joe Nieuwendyk, 40
A fearless forward and skilled face-off specialist who won Stanley Cups with Calgary (1989), Dallas (1999) and New Jersey (2003), Nieuwendyk closed out his career 19th on the all-time goal scoring list (559). He won the Conn Smythe Trophy as playoff MVP in 1999 and an Olympic gold medal with Team Canada three years later.
27 of 30Bob Rosato/SI
Wayne Chrbet, 32
A gutsy, undrafted 5-foot-10 receiver from tiny Hofstra University on Long Island (where the Jets train), Chrebet became the team's second all-time leading receiver during his 11-year-career, but was forced from the sport after suffering at least seven concussions.
28 of 30Kent Smith/Getty Images
Jamal Mashburn, 33
The fourth player taken in the 1993 NBA Draft and career 19.1 points per game scorer, Mashburn was good when he wasn't hobbled. He missed 2004-05 because of an injured right knee and spent the following season on the inactive list after having microfracture surgery on the knee. When Philadelphia waived him last March, he retired after 11 seasons spent with three teams.
29 of 30John Biever/SI
Marquis Grissom, 38
The two-time All-Star and four-time Gold Glove outfielder played for six teams in 17 years and helped the Atlanta Braves win the 1995 World Series. He is one of only six players to amass 200 homers, 400 steals and 2,000 hits.
30 of 30Laurence Griffiths/Getty Images
Roy Keane, 34
One of the most intimidating players in world soccer as well one of Ireland's most decorated, Keane helped Manchester United win seven league titles and four FA Cups between 1993 and 2005. He retired in June due to a hip injury.
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