What are all the examples of utopianism?

This question is a bit open-ended. Since you've posted the question in the literature category, I assume you'd like to know about some classic examples of utopianism in literary tradition.
First, let's define the term. "Utopia" comes from the Greek phrase "no place," and it refers to an imaginary place or state in which everything is perfect. Utopianism, then, is the belief in that place, or the pursuit of it. 
A great example of utopianism is the Garden of Eden in the Bible's Old Testament, a place where "every tree . . . is pleasant to the sight, and good for food." We know what happens next. Adam and Eve disobey the rules and are cast out of the perfect garden, out of the utopia, which becomes only a memory—an idealized place where everything was pleasant.
Another classic example of utopianism can be found in Plato's The Republic (published circa 370 BCE). In Plato's imagined republic, the leaders are intelligent, making decisions for the greater good of the public. Money is unnecessary, and nobody holds individual property; everything belongs to the community.
A more contemporary example of utopianism exists in the work of H. G. Wells, who wrote A Modern Utopia in 1905 and In the Days of the Comet in 1906. In these texts, Wells imagines a world without national boundaries, where people are free to work (or not) and human equality is paramount.