Ahlen (German pronunciation: [ˈaːlən]) is a town in North Rhine-Westphalia, Germany. It is part of the District of Warendorf and is economically the most important town in that district. Ahlen is part of the larger Münster region, and of the historic Münsterland area. The nearby villages of Dolberg, Vorhelm and Tönnishäuschen are part of Ahlen, as well. The largest neighboring town is the city of Hamm to the southwest.

Surrounding Ahlen are the towns of Sendenhorst, Ennigerloh, Beckum, Lippetal, Heessen (District of the city of Hamm) and Drensteinfurt.

Ahlen was first uttered in the Vita Liudgeri II in or about the year 850. Grounds for the name Ahlen, which indeed means "eels", are unknown. A bedecked eel with a crown and feathers fittingly dons the town's coat of arms. The start of the settlement was likely due to there being a crossing over the river Werse, which was also the crossing of two key roads (Hamm–Ahlen–Warendorf and Beckum–Ahlen–Herbern), and the beginning of a third road (Ahlen–Münster). In its early centuries, the fledgling settlement was built around an episcopal court. Within the safe haven of this church fortification, the first settlers were craftsmen and merchants who traded with the local farmers and peasants of the court. Long-distance trading started in the second half of the 12th century — proof being the names of Ahlen merchants found on invoices from merchants in Lübeck. Ahlen was also part of the north German Hanse. During this time a town wall with five towers was built (about 1271). The stripping away of the town wall had begun in the year 1765 and the last hint of it was gone by 1929.