Aleksander Piotr Czekanowski (12 February 1833 – 30 October 1876) was a Polish geologist and explorer of Siberia.Czekanowski was born in Kremenets, Russian Empire, now in Ukraine, and died in Saint Petersburg, Russian Empire.
He participated in the January Uprising (1863), in the aftermath of which he was exiled to Siberia by the Russian authorities.
He took part in and later led several expeditions, surveying and mapping the geology of Eastern Siberia.
He was released from exile in 1875, and in 1876 took up the post of custodian in the Mineralogical Museum of the Academy of Sciences.