<unk>  () is a genus of bacteria that are Gram-positive and most are aerobic. They are bacilli (rod-shaped), and in some phases of life they are, more specifically, club-shaped, which inspired the genus name (coryneform means "club-shaped"). They are widely distributed in nature in the microbiota of animals (including the human microbiota) and are mostly innocuous, most commonly existing in commensal relationships with their hosts. Some are useful in industrial settings such as C. glutamicum. Others can cause human disease, including most notably diphtheria, which is caused by C. diphtheriae. As with various species of a microbiota (including their relatives in the genera Arcanobacterium and Trueperella), they usually are not pathogenic, but can occasionally opportunistically capitalize on atypical access to tissues (via wounds) or weakened host defenses.
Corynebacterium
Mycoplasma
Legionella
Candida 
Streptococcus
Actinobacillus
Bacillus anthracis
Cryptococcus