This study involves an investigational drug called ravulizumab (referred to as study drug). This study drug is being developed to treat generalized Myasthenia Gravis (gMG) by blocking complement activity. Complement activity is part of your immune system which fights against infections. In patients with gMG, abnormal complement activity is present, which causes damage to the structures in the body that are responsible for neuromuscular transmission. The purpose of this study is to evaluate the safety and efficacy of ravulizumab intravenous (IV; in the vein) in subjects with gMG.