Marian Alojzy Łomnicki (9 September 1845 – 26 October 1915) was a Polish geologist, zoologist, paleontologist and encyclopedist.

Łomnicki was born in Baworów in the Ternopil region where his parents Jakub and Magdalena née Borkowski belonged to impoverished noble family of Suchekomnaty.

In Vienna he studied geology under Eduard Suess and paleontology under Rudolf Kner.

He contributed to the geological atlas of Galicia and published two book on zoology.

Łomnicki's wife Maria Szczucka was an activist who had been involved in nationalist movements.