We study authentic leadership as a prominent but problematic example of positive leadership that we use as a more general “warning” against the current fashion of excessive positivity in leadership studies. Without trying to cover “everything”, we critically examine the principal tenets of mainstream authentic leadership theory and reveal a number of fundamental flaws: shaky philosophical and theoretical foundations, tautological reasoning, weak empirical studies, nonsensical measurement tools, unsupported knowledge claims and a generally simplistic and out of date view of corporate life. Even though our study focuses on authentic leadership, much of our criticism is also applicable to other popular positive leadership theories, such as transformational, servant, ethical and spiritual leadership.