From the IMI Citizenship Catalog

⁷A majority of countries have legislative provisions that allow the head of state, supreme court, or national assemblies to grant citizenship, usually without residency or language requirements, to individuals considered of particular merit or utility or in exchange for loosely defined exceptional contributions or services to the country. This path to citizenship is typically applied only in rare circumstances, on a case-by-case basis, and not according to detailed criteria, most commonly to athletes, artists, industrialists, or individuals who have displayed conspicuous acts of heroism.
Chart: IMI (imidaily.com)Created with Datawrapper