Tantanin Clark wani tantanin halitta ne na lantarki da ake amfani da shi azaman ma'auni na farko don auna ƙarfin lantarki (EMF) na wasu ƙwayoyin. Ya ƙunshi mercury/mercurous chloride electrode da zinc electrode da aka nutsar a cikin maganin electrolyte na potassium chloride. An ba wa tantanin Clark sunan mai suna Josiah Latimer Clark, injiniyan lantarki kuma masanin kimiyyar lissafi dan Burtaniya.