Hjalmar Leo Mehr (19 November 1910 – 26 December 1979) was a Swedish Social Democratic politician, mayor of Stockholm (1958–1966, 1970–1971) and governor of Stockholm County (1971–1977). He promoted many radical socialist welfare state policies but is mostly remembered and criticized for the redevelopment of Norrmalm, where a significant part of the old Stockholm was demolished.^[1][2]

In 1969, Mehr was elected president of the newly established Swedish Association of Local Authorities (Svenska Kommunförbundet), an association that existed from 1969 to 2007 (now the Swedish Association of Regions) to interact with the Riksdag of Sweden.

Mehr's parents, Sara and Bernhard Meyerowitch, were Russian-Jewish revolutionaries (mensheviks) who after the failed 1905 Russian Revolution fled to Sweden, where Hjalmar was born and named after Hjalmar Branting.^{[citation needed]}