Theodor Friedrich Ludwig Nees von Esenbeck (26 July 1787 - 12 December 1837, Hyères) was a German botanist and pharmacologist who was a native of Schloss Reichenberg in Reichelsheim (Odenwald). He was a younger brother to naturalist Christian Gottfried Daniel Nees von Esenbeck (1776–1858).
In 1805 Nees von Esenbeck was an apprentice to pharmacist Wilhelm Martius in Erlangen, and in 1811 moved to Basel where he worked for the Bernoulli family at the Goldenen Apotheke. In 1817 his friend, zoologist Heinrich Kuhl (1797–1821) procured an assignment for him at the University of Leiden as a reader of botany, and shortly afterwards, with the help of botanist Sebald Justinus Brugmans (1763–1819), he held a position at the Botanical Gardens in Leiden. In 1818 he earned his doctorate at the university, and subsequently moved to Bonn where he worked at the Botanical Gardens. In 1827 he attained the title of "full professor" at the University of Bonn, where he was a colleague of Ludolph Christian Treviranus (1779–1864).
Nees von Esenbeck is remembered for his systematic research on the medicinal properties of plants. In 1834 with Ludwig Clamor Marquart (1804–1881), Philipp Wilhelm Wirtgen (1806–1870), Johann Carl Fuhlrott (1803–1873) and his older brother, he founded a botanical organization that performed important investigations involving the botany of the Rhineland. The plant genus Neesia in the subfamily Bombacoideae was named after him by botanist Carl Ludwig Blume (1796–1862).