The Château de Bagatelle is a small neoclassical château with a French landscape garden in the Bois de Boulogne in the XVIe arrondissement of Paris. There is also a Château de Bagatelle located near Abbeville in northern France.

The château is a glorified playground, actually a maison de plaisance intended for brief stays while hunting in the Bois in a party atmosphere, which was initially built as a small hunting lodge for the Maréchal d'Estrées in 1720. Bagatelle from the Italian bagattella, means a trifle, or little decorative nothing. In 1775, the Comte d'Artois, Louis XVI's brother, purchased the property from the prince de Chimay. The Comte soon had the existing house torn down with plans to rebuild. Famously, Marie-Antoinette wagered against the Comte, her brother-in-law, that the new château could not be completed within three months. The Comte engaged the neoclassical architect François-Joseph Bélanger to design the building that remains in the park today. The Comte won his bet, completing the house, the only residence ever designed and built expressly for him, in sixty-three days, from September 1777. It is estimated that the project, which came to include manicured gardens, employed eight hundred workers and cost over three million livres. Bélanger's brother-in-law Jean-Démosthène Dugourc provided much of the decorative detail. The central domed feature was a music-room. The master bedroom was fitted up in the manner of a military tent, and Hubert Robert executed a set of six Italianate landscapes for the bathroom. Most of the furnishings were provided by numerous Parisian marchand-merciers, notably Dominique Daguerre; a decorative painter was A.-L. Delabrière.