In 1995, Congress solved the problem of professional plaintiffs in shareholder litigation—or so it thought. The Private Securities Litigation Reform Act (PSLRA) was designed to end the influence of shareholder plaintiffs who had little or no connection to the underlying suit. Yet it may have failed to accomplish its goal. In the wake of the PSLRA, many professional plaintiffs simply moved into other types of corporate lawsuits. In shareholder derivative suits and acquisition class actions across the country, professional plaintiffs are back. They are repeat filers involved in dozens of lawsuits. They are the attorneys’ spouses, parents, and children. They may even be entities created for the primary purpose of filing litigation. These new professional plaintiffs have flown almost entirely under the radar of corporate law scholarship. This Article pulls back the curtain on professional plaintiffs, examining court filings and other public records in the first comprehensive study of professional plaintiffs’ role in corporate law. In most instances, professionalism is a good thing—but not when it comes to choosing plaintiffs.