Bacteria with a rod-shaped structure are termed as Bacilli. Examples include corynebacterium and Clostridium tetani.
Spiral shaped bacteria are called spirilla. Examples include the Campylobacter Spirillum.
Bacteria having a comma-like single curve in their body are Vibrio. Examples include Vibrio vulnificus and Vibrio cholerae.
Bacteria are called cocci which are round in shape. Examples include Staphylococcus aureus and Streptococcus pneumoniae.