An H5U file is a mod file used by Heroes of Might and Magic V, the fifth installment of the Heroes of Might and Magic turn-based strategy game series. It contains game content modification files that alter gameplay, such as creature stats, abilities, textures, animations, and spells. H5U files are compressed .ZIP files but renamed with the ".h5u" extension for organizational purposes.

Heroes of Might and Magic 5 mods allow you to alter game content such as creatures, heroes, skills, and spells. Originally, mods were saved with the .PAK extension but with the 2007 release of the Tribes of the East (ToE) add-on, mods were given the "h5u" extension. H5U files are located in the "UserMODs" folder of the Heroes of Might and Magic 5 directory. If you want to uninstall a mod just remove the corresponding H5U file from the directory. You can unpack the H5U file by renaming the ".h5u" extension to ".zip", then extracting the contents with a Zip decompression program, such as WinZip or WinRAR. NOTE: Heroes of Might and Magic was originally developed by Jon Van Caneghem of New World Computing. The series is now owned by Ubisoft.