Talking about privacy in the public prima facie seems to be a contradiction: why should privacy have to play a role within the public sphere? What could possibly be private in the public? However, quite a number of theories of privacy conceptualize privacy as a protective shield which we carry with us wherever we are: respect for privacy in public then means, for instance, not listening in on private conversations between friends on the street or in a cafe. The most important form of privacy in public, however, which has gained a lot of attention during the last decade or so, is privacy as anonymity: the form of privacy in the public sphere, online as well as offline, which means invisibility, nontraceability, not being identifiable as an individual person. Theories of privacy differ as to the possibility as well as to the desirabilty of anonymity in public contexts, online as well as offline. In my paper, I investigate the complicated relations between privacy, anonymity, and the public sphere. I will, firstly, clarify the conceptual relation between privacy and anonymity, drawing on theories which define privacy in terms of conditions enabling individual freedom and autonomy. I will also review some normatively relevant differences between the online and the offline world. In the second part, I will discuss possible normative conflicts between a moral or legal right to privacy and anonymity, and considerations of security, accountability, or moral responsibility. One of the important questions will concern the ethical consequences of the technical possibilities of identification and de-anonymization in the online world.