Sports agents do not receive a level of attention proportional to their importance. Not only do they negotiate the employment and endorsement contracts of players, but they also are the primary link between the players and the teams they play for. They have great influence on where athletes decide to play and in some cases have great influence on the finances of athletes. Sports agents generally receive between 4% and 10% of the athlete's playing contract, and 10% to 20% of the athlete's endorsement contract, although these figures vary between sports. The list below represents the ten most powerful agents based on the contracts they negotiated as of 2013. The contract figures were based on an article published in Forbes Magazine. All four major North American sports are represented in this list (NFL, NHL, NBA and MLB).

10. Dan Lozano - Current Contracts Negotiated $540.78 Million

Dan Lozano is a sports agent who specializes in baseball. He is the founder of the Los Angeles based sports agency, MVP Sports Group. He represents some of the biggest names in Major League Baseball (MLB) including Albert Pujols, Joey Votto, Alex Rodriguez and Carlos Beltran. Lozano has negotiated some of the biggest contracts in MLB history including Pujols' $240 million contract with the Los Angeles Angels of Anaheim and Joy Votto's $225 million contract extension with the Cincinnati Reds. Lozano also negotiated Mike Piazza's 7-year, $91 million contract with the New York Mets in 1998, which was the largest MLB contract at the time.

9. J.P. Barry - Current Contracts Negotiated $547.85 Million

J.P. Barry is the co-head of the Hockey division of Creative Artists Agency along with Pat Brisson. He represents some of the premier hockey players currently playing in the National Hockey League (NHL). A list of the players that Barry represents includes Sidney Crosby, Daniel Briere, Anze Kopitar, Dany Heatley, Evgeni Malkin and Roberto Luongo. In 1995, Barry started working as a counsel for the NHL Players Association (NHLPA). Barry's stint with the NHLPA lasted until he joined the sports agency, IMG, in 1998. Barry worked at IMG until he joined Creative Artists Agency in 2006.

8. Rob Pelinka - Current Contracts Negotiated $595.15 Million

Rob Pelinka is best known for being a member of the University of Michigan's three Final Four teams between 1989-1993 and for being the agent of one Kobe Bryant. Pelinka is the President and CEO of The Landmark Sports Agency. Along with Kobe Bryant, Pelinka represents other NBA stars such as Andre Iquodala, Carlos Boozer, James Harden and Eric Gordon. Before founding the Landmark Sports Agency, Pelinka worked for the SFX management agency. While working for SFX Pelinka was involved in the controversy between Carlos Boozer and the Cleveland Cavaliers. Boozer reportedly failed to honor an agreement with Cavalier management who let him out of the final year of his contract so he could sign a 6-year, $41 million contract. Instead Boozer signed a 6-year, $68 million contract with the Utah Jazz. Pelinka was attacked in the press and left SFX, who also dropped Boozer as a client.

7. Sam and Seth Levinson - Current Contracts Negotiated $660.1 Million

Sam and Seth Levinson are the heads of the ACES sports agency. ACES is an acronym for Athletes' Careers Enhanced and Secured. They are the second agents on this list that specialize in baseball. The ACES sports agency has represented baseball players for more than 25 years. A list of some of the major clients that are represented by the Levinson brothers include Brandon Philips, David Wright, Dustin Pedroia and Jonathan Papelbon. In 2012, the ACES agency was involved in some controversy for allegedly being involved in the creation of fake websites to explain the positive steroid test of their client Melky Cabrera.

6. Jeff Schwartz - Current Contracts Negotiated $793.95 Million

Jeff Schwartz is the founder and head of the Excel Sports Management agency. Schwartz began his management career in 1992 with the International Management Group (IMG) and represented some of the biggest names in tennis such as Pete Sampras and Martina Hingis. Schwartz established the Excel Sports Management agency in 2002 and has represented some of the biggest names in basketball since. A list of Schwartz' clients include Paul Pierce, Blake Griffin, Kevin Love and Jason Kidd. In 2011, Excel expanded into a multi-sports agency with the addition of agents specializing in other sports and currently represents baseball stars such as Derek Jeter and Ryan Howard and golf's most recognizable name, Tiger Woods.

5. Ben Dogra - Current Contracts Negotiated $948.82 Million

Ben Dogra is the co-head of the football division of Creative Artists Agency (CAA) along with Tom Condon. CAA football is the primary reason behind the agency’s overall number one ranking on Forbes’ list of most valuable sports agencies in the world. CAA' football practice is worth more by itself as a single sport division, than any other multi-practice agency in the world. Dogra has represented more first round picks in the NFL than any other agent since 2004. A list of Dogra' clients in the NFL include Carl Nicks, DeMeco Ryans, Mario Williams, Trent Williams, Patrick Willis and Robert Griffin III.

4. Arn Tellem - Current Contracts Negotiated $987.98 Million

Arn Tellem is the Vice Chairman of the Wasserman Media Group (WMG). Tellem, who many consider to be one of the most influential agents in professional sports, leads Wasserman’s basketball practice and has helped propel the agency to third on Forbes’ list of most valuable sports agencies in the world. A list of Tellem' clients include Joe Johnson, Derrick Rose, Marc Gasol, Russell Westbrook, LaMarcus Aldridge, Al Horford and 2012 1st overall pick Anthony Davis. As of December 1st, 2013, Tellem ranked first among NBA player agents in players represented with 43, All-Stars with 9, and maxed-out contracts with 6. Tellem has also represented players in baseball and has helped negotiate contracts for Jason Giambi, Mike Mussina, Chase Utley and Yu Darvish.

3. Drew Rosenhaus - Current Contracts Negotiated $1.08 Billion

Drew Rosenhaus is one of the most recognizable agents in sports and is head of the Rosenhaus Sports Representation agency. He is most famous for being the agent of former NFL wide receiver Terrell Owens and managing to get Willis McGahee selected in the first round of the 2003 NFL draft despite suffering a serious knee injury. Rosenhaus is known for using aggressive tactics on behalf of his clients who play exclusively in the NFL. Rosenhaus has been accused of contacting NFL players that are represented by other agents and using his clients to recruit other clients, both of which are against NFL rules. Current Rosenhaus clients include Antonio Brown, Charles Johnson, Darnell Dockett, Rob Gronkowski and NaVorro Bowman.

2. Tom Condon - Current Contracts Negotiated $1.32 Billion

Second on this list is veteran football agent Tom Condon, who co-heads Creative Artist Agency’s football division with the aforementioned Ben Dogra. Condon, a former NFL player himself, has negotiated an estimated $1.32 billion in current player contracts. He also served as the President of the NFL Players Association from 1984-1986. Combined with Dogra and other agents, CAA represents more than $2.9 billion dollars and 479 years of current NFL player contracts. Condon started representing NFL players while he was still an active player. A list of current players that are represented by Condon include Drew Brees, Eli Manning, Peyton Manning, Antonio Gates, Matthew Stafford and Sam Bradford.

1. Scott Boras - Current Contracts Negotiated $1.66 Billion

The most powerful agent in sports according to this list is baseball's Scott Boras, who is head of the Boras Corporation. Boras has negotiated over $1.6 billion in current contracts. Not only has he carried himself to the very top of the sports agent business, but has also made Boras Corporation the second most valuable sports agency in the world according to Forbes, even among those agencies that represent all other major team sports combined. Boras currently represents several star MLB players including Stephen Strasburg, Prince Fielder, Matt Holliday, Jayson Werth, Barry Zito and Jered Weaver. Boras used to represent both Alex Rodriguez and Mark Teixeira and helped them sign their current contracts which are the largest and tenth largest contracts in MLB history, respectively.