Hjalmar Leo Mehr (1910–1979) 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.
Hjalmar Mehr's parents, Sara and Bernhard Meyerowitch, were Russian-Jewish revolutionaries who after the failed 1905 Russian Revolution fled to Sweden, where Hjalmar was born and named after Hjalmar Branting.