Some professional athletes compete in violent sports that involve frequent physical contact and the potential for serious injuries. Some professional athletes take risks in their chosen sports in the hopes of achieving greater success and potential financial gains. This chapter considers violent and risky behaviors of professional athletes using an economic lens. These behaviors might increase the expected return from their sports by increasing the financial rewards that come with success and improving the odds of success. However, these behaviors are usually penalized by their sports, if detected, or penalized by social norms that are enforced by fans. Hence, professional athletes must consider the benefits and costs from committing violent or risky behaviors. While there are many sports that feature, or even require, violent behavior, this chapter focuses on players from the National Football League (NFL) and the National Hockey League (NHL) in North America, their injuries, and subsequent