Theodore Erasmus Hilgard (7 July 1790 Marnheim - 14 February 1873 Heidelberg) was a lawyer, viticulturalist and Latin farmer.
He grew up during the Napoleonic Wars in a family very sympathetic to the principles of the French revolution. He studied at the Universities of Heidelberg (1807), Göttingen (1808-9) and Paris (1810), and took a legal course in Coblenz (1811). During the time of the French rule, he practiced law in Trèves, and, on the restoration of the Rhine Province to Germany, settled in Zweibrücken, where he held the appointment of associate justice of the court of appeals from 1821 till 1835. He was also a member of the provincial assembly from 1821 till 1826. He resigned as justice because of reactionary and bureaucratic policies instituted by the Bavarian government in the administration of justice in the Palatinate. In 1816, he married Margarethe Pauli.
In 1835 he came to the United States, and settled in St. Clair County, Illinois. He purchased a farm near Belleville, and besides its general management gave much attention to viticulture, being the first to introduce it in Illinois. At first he tried to discover which of the Rhenish or French vines were best adapted to the climate, but soon found the indigenous Catawba grape most suitable, and he produced a wine that acquired a high local reputation.
The town of West Belleville, which gradually surrounded his original homestead, was laid out on his property and under his direction. He profitably sold a large part of his land as house lots. Meanwhile, he gave special attention to the education of his children, whom he instructed personally in mathematics, languages and philosophy.-