Siegfried Reissek (11 April 1819 in Teschen – 9 November 1871 in Vienna) was an Austrian naturalist and botanist who specialized in spermatophytes.
He is known for his studies involving plant anatomy and histology.From 1837 to 1841 he was a student at the University of Vienna.
He worked as assistant curator at the Royal Botanical Collection in Vienna between 1845 and 1867, when he was appointed head curator; and from 1848 was a member of the Vienna Academy of Sciences.
He circumscribed numerous plant taxa, including the genus Stenanthemum (family Rhamnaceae).
The plant genus Reissekia (family Rhamnaceae) commemorates his name.