The Codex Manesse, Manesse Codex, or Große Heidelberger Liederhandschrift is an illuminated manuscript in codex form copied and illustrated between ca. 1304 when the main part was completed, and ca 1340 with the addenda; the codex was produced in Zürich at the request of the Manesse family of Zürich. The possibility that the compiler was the Minnesinger Johannes Hadlaub provided the subject of a poetic novella, "Hadlaub" (in the Züricher Novellen, 1878), by Gottfried Keller. It is the single most comprehensive source for the texts of love songs in Middle High German, representing 140 poets, several of whom were famous rulers. The term for these poets, Minnesänger, combines the words for "romantic love" and "singer", reflecting the content of the poetry, which adapted the Provençal troubadour tradition to German.

The manuscript is "the most beautifully illumined German manuscript in centuries;" its 137 miniatures are a series of "portraits" depicting each poet. A large number of the nobles are shown in full armour in their heraldic colors and devices (therefore with their faces hidden) taking part in tournament combats. Many designs draw their motifs from the names of the poets (Dietmar is shown riding a mule, since his name can be interpreted as meaning people's horse) or on imagery from their lyrics (Walther von der Vogelweide is shown in a thoughtful pose which exactly matches the description of himself in one of his most famous songs). Since the manuscript was compiled up to 100 years after the deaths of some of the poets, neither the likenesses nor the heraldry can be regarded as authentic, though they have been widely reproduced.

The entries are ordered approximately by the social status of the poets, starting with the Holy Roman Emperor Henry VI, Kings Conradin and Wenceslaus II, down through dukes, counts and knights, to the commoners.

The codex had an obscure early history before it belonged to the Baron von Hohensax, when Melchior Goldast published excerpts of its didactic texts. After 1657 it was in the French royal library, from which it passed to the Bibliothèque Nationale, where the manuscript was studied by Jacob Grimm in 1815. In 1888, after long bargaining, it was sold to the Bibliotheca Palatina of Heidelberg, following a public subscription headed by William I and Otto von Bismarck.

The first critical editions of the Codex Manesse appeared in the early nineteenth century. The codex is frequently referred to by Minnesang scholars and in editions simply by the abbreviation C, introduced by Karl Lachmann, who used A and B for the two main earlier Minnesang codices
(the Kleine Heidelberger Liederhandschrift and the Weingartner Liederhandschrift respectively).

Two leaves of a 15th Century copy of the manuscript, called the Troßsche Fragment (Tross Fragment), were held in the Berlin State Library, but went missing in 1945.