Slidell is a city on the northeast shore of Lake Pontchartrain in St. Tammany Parish, Louisiana, United States. The population was 28,781 at the 2020 census. It is part of the New Orleans−Metairie−Kenner metropolitan statistical area.

John Slidell was an American politician, lawyer, slaveholder, and businessman. A native of New York, Slidell moved to Louisiana as a young man and became a Representative and Senator. He was one of two Confederate diplomats captured by the United States Navy from the British ship RMS Trent in 1861 and later released. He was the older brother of Alexander Slidell Mackenzie, a U.S. naval officer.