Severe colitis, an umbrella encompassing several entities, is one of the most common acute gastrointestinal disorders resulting in critical illness. Clostridium difficile infection is responsible for the majority of nosocomial diarrhea with fulminant C difficile colitis (CDC) carrying a high mortality. Optimal outcomes can be achieved by early identification and treatment of fulminant CDC, with appropriate surgical intervention when indicated. Ischemic colitis, on the other hand, is uncommon with a range of etiological factors including abdominal aortic surgery, inotropic drugs, rheumatoid diseases, or often no obvious triggering factor. Most cases resolve with nonsurgical management; however, prompt recognition of full-thickness necrosis and gangrene is crucial for good patient outcomes. Fulminant colitis is a severe disease secondary to progressive ulcerative colitis with systemic deterioration. Surgical intervention is indicated for hemorrhage, perforation, or peritonitis and failure of medical therapy to control the disease. Although, failure of medical management is the most common indication, it can be difficult to define objectively and requires a collaborative multidisciplinary approach. This article proposes some simple management algorithms for these clinical entities, with a focus on critically ill patients.