There are two ants which are the biggest of all ants. They are the Australian bulldog ant and the African driver ant both of which can grow to sizes larger than 4 cm in length.
The Bulldog ants are vicious and aggressive in nature and are also known as Bull ants or Inch ants. These ants also have a powerful sting that can induce an anaphylactic shock if stung. The reaction can be powerful and possibly cause death.
Also, the Queen of the ants is biggest out of all the ants. She is always larger in size no matter what colony or species of ant.