There are 5 million fungal species. However, the discovery and classification of fungi are in high flux. Modern concepts indicate that the three kingdoms of “fungi” are Chromista, Fungi and Protozoa. Strong support for the wrong phylogeny can occur without correct analytical methods. In the current Collection we envisaged fungi representing extremely diverse and ancient eukaryotic organisms, with familiar groups such as mushrooms, yeasts and “moulds”. We collected 6 fascinating papers in three areas of Diversity, Chemical Diversity and Evolution.