Luc Siméon Auguste Dagobert de Fontenille (8 March 1736, La Chapelle-en-Juger, near Saint-Lô, Manche – 18 April 1794, Puigcerdà) was a French general of the French Revolutionary Wars.
Descendent of a noble family, Dagobert de Fontenille was major of the bataillon de chasseurs royaux du Dauphiné in 1788. Sous-lieutenant in the régiment de Touraine, he served in the Seven Years' War as an officer in Le Royal-Italien, and remained in that unit for the Corsican campaign of 1769. Whilst on Corsica he came into direct contact with the Bonaparte family.
By his marriage on 8 August 1780 to Jacquette Pailhoux de Cascastel (daughter of a Conseiller souverain of Le Roussillon), he became master of the forges and formed a company to exploit the mines at Les Corbières and Le Razès under the jurisdiction of the abbey of Lagrasse with his cousin, Jean-Pierre François Duhamel, correspondent of the Académie des sciences and commissaire of Louis XVI for mines and forges.
In 1789, he and Louis-Philippe d'Orléans, grand-maître of the "Grand Orient de France", rallied to the revolutionary cause. He was made colonel in May 1792, at the outbreak of the War of the First Coalition, and sent to the armée du Var, in which he had many successes. Moved to the armée d'Italie under d'Anselme and Biron, he distinguished himself before Nice and at the col de Negro.
When the French National Convention declared war on Spain on 7 March 1793, de Fontenille moved to the armée des Pyrénées orientales, under general de Flers, and commanded an entrenched camp of 8,000 men. He repulsed a Spanish attack on this position on 19 May but was still forced to abandon it, though he then stopped an enemy column of 6,000 men marching on Perpignan. Made commander in chief of the armée centrale des Pyrénées after de Flers was removed from this post, he seized Puycerda on 29 August 1793 and the whole of the Spanish Cerdagne within 24 hours, before defeating the Spanish again on 4 September 1793 at Montlouis, capturing 14 cannon and recapturing part of Le Roussillon.