Esmark is a surname. Notable people with the surname include:

• Birgitte Esmark (1841–1897), Norwegian malacologist

• Jens Esmark (1763–1839), Danish-Norwegian mineralogist, study of glaciers

• Lars Mathias Hille Esmark (1908–1998), Norwegian civil servant

• Morten Thrane Esmark (1801-1882), Norwegian priest and mineralogist

See also

• Esmark Inc., an American company founded in 2008, operating mainly in the steel industry

• Esmark Glacier, glacier in South Georgia Island

• Esmarkbreen, glacier in Svalbard

• JBS USA, successor of former holding company Esmark