Former Miami Dolphins quarterback Dan Marino has been soaked as an investor in a digital media company founded by "Titanic" director James Cameron. The company is best known for creating a 3-D holographic image of the late East Coast rapper Tupac Shakur performing at the Coachella festival in Indio, Calif., in April.

But now Port St. Luice, Fla.-based Digital Domain Media Group, Inc. is a shadow of its former self, and Marino's 1.6 million shares in the company are worth bupkis. The company had been involved in special effects for films such as "Transformers" and the "Pirates of the Caribbean" franchise, but not even Cameron's clout and his $700 million net worth could rescue the company from insolvency.

Digital Domain went public 10 months ago, floating 5 million shares that were snatched up for $8.50. The price surged to $9.20 after Tupac's holographic "appearance" and ensuing deals to create a holographic Elvis for public performances and media projects, according to the West Palm Beach, Fla., ABC affiliate.

But the company violated lenders' terms and failed to convince even near-billionaire Cameron to provide enough capital to meet operating requirements.  

By the time Digital Domain went into Chapter 11 bankruptcy court on Tuesday, shares were worth 55 cents. By Thursday afternoon they were trading on the PINK sheets for 10 cents. Marino is estimated to have lost $13.6 million -- a considerable amount even for a retired football superstar who still holds 16 NFL records. Celebrity Net Worth says Marino's net worth is about $35 million.  

Marino is not alone in the world of failed NFL quarterback entrepreneurs. Here are five others that fumbled the investment ball.

Johnny Unitas, aka The Golden Arm, the record-setting Baltimore Colts quarterback from the 60s, wasn’t such a great investor. He lost in ventures that included bowling alleys and restaurants. His biggest flop, the one that sent him to bankruptcy, was investing in a circuit board manufacturer. Unitas, who in his later years was hobbled by artificial knees and was unable to use his right hand, became a champion for better protective gear for football players. Unitas Management Corp., which handled the football great’s finances went bankrupt in 2002. Unitas died the same year at the age of 69.

John Elway, who led the Denver Broncos to five Super Bowls (winning two of them), took a $15 million hit in the $150-million Kirk Wright ponzi scheme that targeted NFL players and led to a lawsuit against the Players Association and the NFL for allowing the fund manager to be listed as a recommended financial advisor. Wright’s International Management Associates was so convincing star defensive backs Blaine Bishop and Steve Atwater became recruiters. Other than this flop, Elway, 52, has been a relatively successful businessman in his post-quarterback years. He has owned car dealerships and steak houses, is an NFL writer and co-owner of the Colorado Crush arena football team.

Michael Vick, who is also quarterback for the Philadelphia Eagles, filed for bankruptcy in 2007 after failing to work out a deal with his creditors. Three of his biggest unsecured lenders were Richmond, Va.-based business services provider Joel Enterprises Inc., Royal Bank of Canada (TSE:RY) and his former team the Atlanta Falcons. Vick, who is 32, owed money to several others. The top seven lenders were owed $12.8 million, though the total bill was estimated to be as high as his $50 million net worth at the time. According to the Atlanta-Journal Constitution, Vick’s finances were in such disarray the bankruptcy judge demanded a trustee, saying Vick had limited ability to handle his own finances.

Weighed down by $25 million in debt incurred by his real estate ventures, Mark Brunell, the 41-year-old free agent for the New York Jets filed for bankruptcy in 2010. The former Washington Redskins quarterback holds a record for the most consecutive completions in a single game (22). Brunell has talked of retiring recently and has said his experience in failure has reaffirmed his faith in God and family.

There’s nothing Oakland Raiders quarterback Matt Leinart has done to lose capital he earned, but his decision to linger for another year at University of Southern California a year after winning the Heisman Trophy and leading the USC Trojans to victory in the BCS National Championship Game ultimately hurt his draft stock. He was widely believed to be the best NFL prospect heading into the 2005 NFL draft, and had he entered the draft he would have likely been selected No. 1 by the San Francisco 49ers and received the $24 million guaranteed that went to Alex Smith. Instead he decided to stay at USC for another year and give critics more time to analyze his flaws as a quarterback, and his draft stock suffered for it. In 2006 he drafted 10th overall by the Arizona Cardinals, and received only $14 million in guaranteed money. Let’s hope that $10-million year at USC was worth it.