1. Coccus (plural: cocci): These bacteria are spherical in shape. Some common examples of cocci include Streptococcus, Staphylococcus, and Neisseria.

2. Bacillus (plural: bacilli): These bacteria are rod-shaped. Some common examples of bacilli include Escherichia coli, Bacillus subtilis, and Salmonella.

3. Vibrio (plural: vibrios): These bacteria are comma-shaped. Some common examples of vibrios include Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus.

4. Spirillum (plural: spirilla): These bacteria are spiral-shaped. Some common examples of spirilla include Treponema pallidum, Borrelia burgdorferi, and Leptospira interrogans.