Once again The Blackstone Group is at the center of a headline-grabbing controversy.

    After the tragic death of SeaWorld trainer Dawn Brancheau last week, Hollywood's animal rights advocates grabbed the moment to criticize the attraction's new owner. Private-equity giant Blackstone bought SeaWorld and nine other theme parks from Anheuser-Busch InBev for $2.3 billion last October.

    TV host Bob Barker, a long-time animal-rights supporter, staged the first call for SeaWorld to shut down. "I must appeal to you to take strong action now so that it never happens again," he wrote in a letter to Blackstone's COO, Tony James, the day after Brancheau's death.

    Matt Damon later told Entertainment Tonight at the premiere of his new film Green Zone, "I think they should just shut them all down. I've never been a fan of places like that."

    But for all of last week's protestations, the show went on. Just three days after Brancheau's death, 2,200 people returned to watch SeaWorld's killer whales perform.

    It's not the first time Blackstone (BX) has been a target. Ever since it moved into the public spotlight with an IPO in 2007, the private-equity firm and its billionaire chief, Steve Schwarzman, have made a few enemies -- many with far more pull than Barker and Damon. Here are a few of them.

    The employees of Travelport

    Blackstone bought the travel services company, which owns a stake in Orbitz.com, for more than $4 billion in 2006. Soon after, it started slashing jobs. Within two months, Travelport had laid off more than 800 people, or 10% of its workforce, according to the Wall Street Journal. Then the company borrowed $1.1 billion to pay a dividend to Blackstone and a partner. Both made their money back in just seven months, according to the Journal. Meanwhile, an additional 1,500 workers took buyouts.

    Sander Levin, U.S. Congressman

    The private equity industry was less than thrilled when Blackstone's IPO highlighted how private equity funds were being taxed. Carried interest, or the 20% of profits usually taken by private equity firms, is taxed well below the corporate rate. After Schwarzman made headlines for cashing in $700 million of stock from the IPO, lawmakers took notice. Rep. Sander Levin, a Michigan Democrat, introduced a bill that would more than double the rate. So far the congressman's efforts have gone nowhere, but President Obama has included the hike in his 2011 budget blueprint.

    The SEC

    Last fall the Securities and Exchange Commission was considering a rule to ban middleman who solicit money for private equity funds from large investors. The rule was in response to the pay-to-play scandal at many states' retirement funds. Smack in the middle of the cross hairs was Blackstone, which pays "placement agents" to help it raise capital. Schwarzman defended the agents, writing in a five-page letter posted on the S.E.C.'s web site that Blackstone relied on these third parties to raise $850 million for its first private-equity fund. Regulators haven't yet made a final decision.

    Its Own CEO

    Steve Schwarzman threw himself a 60th birthday party few have forgotten. The $3 million soiree in Manhattan's Park Avenue Armory in February 2007 marked a peak to the modern gilded age. Rod Stewart was the main attraction. Patti LaBelle sang Happy Birthday. If anyone had any doubt about the private-equity leader's love of lavish spectacles, five hundred guests dining on lobster and filet mignon sealed the deal.

    Henry Kravis

    The buyout legend and co-founder of Kohlberg Kravis Roberts & Co. leads one of Blackstone's biggest rivals. A feud between Schwarzman and Kravis grew after Blackstone's IPO and his elaborate birthday party. According to a Vanity Fair profile of the two men in 2007, Kravis was furious that Schwarzman brought so much attention to the private equity industry. Lawmakers soon swarmed in with new tax proposals. Kravis later snubbed his rival by not attending a New York Public Library fundraiser hosted in Schwarzman's honor, according to the profile, though it also cited a spokesperson who explained that Kravis was out of town that night.

    Starwood Hotels

    Last April Starwood (HOT, Fortune 500) sued Hilton Hotels, which is owned by Blackstone, and accused two Hilton executives of using a confidential formula to start a new hotel line called Denizen. Both executives have since left Hilton, and lawyers for the two said a criminal investigation would not reveal grounds for criminal charges, The Times of London reported last year. But Starwood took it a step further in January and accused Hilton CEO Christopher Nassetta of knowing that his executives had proprietary Starwood documents, though the lawsuit did not name him as a defendant. Hilton denies liability in Starwood's lawsuit. Last month a federal court filing indicated that prosecutors were investigating criminal charges in the alleged fraud. The espionage case is still pending.

    Investors

    Blackstone went public in June 2007 just in time to make its executives rich and its stock a dud. Schwarzman and co-founder Pete Peterson were instant billionaires. But the stock, which priced at $31 for its IPO, fell below $22 by that September. Overall, shares have lost 54% of their value since listing.