The Hesbaye (French, French pronunciation: [ɛsbɛ]), or Haspengouw (Dutch and Limburgish, Dutch pronunciation: [ˈɦɑspə(ŋ)ˌɣʌu]), is a traditional cultural and geophysical region in eastern Belgium. It is a loamy plateau region which forms a watershed between the Meuse and Scheldt drainage basins. It has been one of the main agricultural regions in what is now Belgium since before Roman times, and specifically named in records since the Middle Ages, when it was an important Frankish pagus or gau, called Hasbania in medieval Latin.

Major parts of three Belgian provinces are dominated by the Hesbaye landscape, important for both tourism and agriculture, and by some definitions it stretches further:

Geographically, Hesbaye borders on several similar regions of rolling hills:

In contrast, to the north it borders on the flat sandy Kempen region. And over the Meuse to the southeast are the rocky hills of the Ardennes. In the west the plateau ends at the Dyle river valley, except to its south where a smaller extension of the plateau landscape stretches into Hainaut and between Brussels and Charleroi, sometimes referred to as the "plateau brabançonne".

The Hesbaye is often divided into two divisions based on stratigraphy, with the boundary running through Sint-Truiden, Borgloon and Tongeren in Dutch-speaking southern Limburg. The northern "Humid" Hesbaye (Dutch Vochtig Haspengouw, French Hesbaye Humide) has a higher water table due to the Tongrian and Rupelian clay-containing layers near the surface, and many springs. It is by far the main fruit growing area of Belgium, as well as home to some of the most northerly vineyards in Belgium. The southern "Dry" division is somewhat more fertile and the ground water sinks more easily; in this region sugar beet, chicory, flax, rapeseed and grains (90% of which is wheat and barley) are cultivated.

In the oldest Latin documents the name of the pagus (country or territory) was typically Hasbania. As demonstrated in the collection of such records given by Ulrich Nonn, this was generally given in an adjectival form such as pagus hasbaniensis. Only a small number of such records added the Germanic word gau or gouw. Verhelst (p. 245 n.45) proposed that the small number cases of medieval Latin which include the "gau" ending are un-coincidentally in or near the old deaconry of Tongeren, which he proposed to be the historical core of the Hesbaye. Therefore, he proposed, the terms Hasbania and Haspengouw can not be assumed to have identical meanings in all records, even though in modern Dutch the form with "gouw" is now the only one, while in modern French the form without is the only one.

Latin continued to be use in documentation in the Belgian area into the early modern era, and it has been noted that spelling variations sometimes even included Hispania (or similar) which would usually refer to geographical area containing Spain and Portugal.

In Roman times, Haspengouw formed the fertile agricultural core area of the Civitas Tungrorum, containing its capital in Tongeren, and with sandy Toxandria to the north of it in the Campine, and the stony hills of the Condroz and Ardennes to the south. The Salian Franks were allowed to settle in Toxandria in the 4th century, while the more heavily populated Haspengouw remained more Romanized. Frankish power however eventually extended over neighbouring Romans. From at least the eighth century Hesbaye was an important geographical division in the Merovingian Frankish kingdom of Austrasia.