Ettlingen (German pronunciation: [ˈɛtlɪŋən] ^ⓘ; South Franconian: Eddlinge) is a town in Baden-Württemberg, Germany, about 8 kilometres (5 mi) south of the city of Karlsruhe and approximately 15 kilometres (9 mi) from the border with Lauterbourg, in France's Bas-Rhin department. Ettlingen is the second largest town in the district of Karlsruhe, after Bruchsal.

Ettlingen is situated at the northern edge of the Black Forest on the Upper Rhine Plain. The Alb River arises in the hills of the Black Forest and flows through Ettlingen before emptying into the Rhine at Eggenstein-Leopoldshafen, making Ettlingen a central feature of the Albtal, the Alb Valley. Central Ettlingen and its largest constituent communities (Bruchhausen, Ettlingenweier, Oberweier) lie on the plain itself, but some of the villages (Spessart, Schöllbronn, and Schluttenbach) are nestled among the northernmost foothills of the Black Forest.

The municipality of Ettlingen is bordered by the following communities, clockwise from the north: Karlsruhe, Waldbronn, Karlsbad (Baden), Marxzell, Malsch, and Rheinstetten, all of which belong to the district of Karlsruhe, except for the independent city of Karlsruhe itself.

Since the major communal reforms enacted by Baden-Württemberg in the early 1970s, the municipality of Ettlingen has consisted of the town of Ettlingen itself and the communities of Bruchhausen, Ettlingenweier, Oberweier, Schluttenbach, Schöllbronn, and Spessart.

Ettlingen was an important crossroads during Roman times, when the region was part of the province of Germania Superior. This is demonstrated by the many artifacts found in the area, including the "Neptune Stone," which commemorates a flood of the Rhine, and the remains of a Roman bath excavated beneath St. Martin's Church. The town was first mentioned in 788 as "Ediningom" in a deed of donation belonging to Weissenburg Abbey in Alsace (now in France). In 965, the village of Ettlingen ("Ediningom") received market rights (Marktrecht) from Emperor Otto the Great. In 1192, Emperor Henry VI, one of Frederick Barbarossa's sons. Margrave Herman V of Baden-Baden became Ettlingen's feudal lord in 1219. In the following centuries, Ettlingen developed into an important administrative centre within the Margraviate of Baden-Baden.

Ettlingen gave its name to a line of defensive earthworks known as the Ettlingen Line built to deter French aggression. During the Nine Years' War the town was nearly completely burned to the ground by the troops of Louis XIV, but was nevertheless rebuilt in the following decades under Margravine Sibylle Auguste. After the Catholic line of Baden-Baden died out in 1771, Ettlingen passed to the Protestant Margraviate of Baden-Durlach, which would become the reunited Margraviate of Baden. During the French Revolutionary Wars, Ettlingen was the site of a battle between elements of the French Army of the Rhine and Moselle and the Habsburg Army of the Upper Rhine on 9 July 1796. In the period of Napoleon's activities in Germany, Margrave Karl Friedrich of Baden was made Elector in 1806 and Grand Duke in 1806.

Ettlingen remained an independent town until 1937, when it was incorporated into the administrative unit that would become the district of Karlsruhe in 1939. Ettlingen and its surrounding villages and land continue to be part of this district.

In 1966, Ettlingen passed the 20,000 population mark and raised to the status of Große Kreisstadt by the state government of Baden-Württemberg. During the communal reforms of the early 1970s, several smaller communities were incorporated into Ettlingen, raising the population to over 30,000. Ettlingen's renowned open-air theater series, the Schlossfestspiele first took the stage in the Baroque inner courtyard of Ettlingen Palace in 1979.