Carl Ludwig Sigmund von Ilanor (27 August 1810 – 1 February 1883) was an Austrian syphilologist born in Schässburg (Sighişoara), Transylvania.
He studied medicine and surgery at Josephs-Akademie in Vienna, earning his doctorate in 1837 at the University of Pest. In 1842 he became the senior surgical doctor at the Allgemeines Krankenhaus in Vienna, and during the following year received his habilitation. In 1849 he became a full professor at the University of Vienna and director of the syphilology clinic. He died on 1 February 1883 on a journey to Padua.
In addition to his written works on syphilis and its treatment, he published a number of works in the field of balneology. His name is associated with "Sigmund's glands", also known as epitrochlear lymph nodes.