George Herbert Mead
Symbolic interaction was conceived by George Herbert Mead and Charles Horton Cooley. Mead argued that people's selves are social products, but that these selves are also purposive and creative, and believed that the true test of any theory was that it was "useful in solving complex social problems". Mead's influence was said to be so powerful that sociologists regard him as the one "true founder" of the symbolic interactionism tradition. Although Mead taught in a philosophy department, he is best known by sociologists as the teacher who trained a generation of the best minds in their field. Strangely, he never set forth his wide-ranging ideas in a book or systematic treatise. After his death in 1931, his students pulled together class notes and conversations with their mentor and published Mind, Self and Society in his name. It is a common misconception that John Dewey was the leader of this sociological theory; according to The Handbook of Symbolic Interactionism, Mead was undoubtedly the individual who "transformed the inner structure of the theory, moving it to a higher level of theoretical complexity". Mind, Self and Society is the book published by Mead's students based on his lectures and teaching, and the title of the book highlights the core concept of social interactionism. Mind refers to an individual's ability to use symbols to create meanings for the world around the individual – individuals use language and thought to accomplish this goal. Self refers to an individual's ability to reflect on the way that the individual is perceived by others. Finally, society, according to Mead, is where all of these interactions are taking place. A general description of Mead's compositions portray how outside social structures, classes, and power and abuse affect the advancement of self, personality for gatherings verifiably denied of the ability to characterize themselves.
Herbert Blumer, a student and interpreter of Mead, coined the term and put forward an influential summary: people act a certain way towards things based on the meaning those things already have, and these meanings are derived from social interaction and modified through interpretation. Blumer was a social constructionist, and was influenced by John Dewey; as such, this theory is very phenomenologically-based. Given that Blumer was the first to use symbolic interaction as a term, he is known as the founder of symbolic interaction. He believed that the "Most human and humanizing activity that people engage in is talking to each other." According to Blumer, human groups are created by people and it is only actions between them that define a society. He argued that with interaction and through interaction individuals are able to "produce common symbols by approving, arranging, and redefining them." Having said that, interaction is shaped by a mutual exchange of interpretation, the ground of socialization.
While having less influential work in the discipline, Charles Horton Cooley and William Isaac Thomas are considered to be influential representatives of the theory. Cooley's work on connecting society and the individuals influenced Mead's further workings. Cooley felt society and the individuals could only be understood in relationship to each other. Cooley's concept of the “looking-glass self”, influenced George Herbert Mead’s theory of self and symbolic interactionism. William Isaac Thomas is also known as a representative of symbolic interactionism. His main work was a theory of human motivation addressing interactions between individuals and the "social sources of behaviors." He attempted to "explain the proper methodological approach to social life; develop a theory of human motivation; spell out a working conception of adult socialization; and provide the correct perspective on deviance and disorganization."  A majority of scholars agree with Thomas. 
Two other theorists who have influenced symbolic interaction theory are Yrjö Engeström and David Middleton. Engeström and Middleton explained the usefulness of symbolic interactionism in the communication field in a variety of work settings, including "courts of law, health care, computer software design, scientific laboratory, telephone sales, control, repair, and maintenance of advanced manufacturing systems". Other scholars credited for their contribution to the theory are Thomas, Park, James, Horton Cooley, Znaniecki, Baldwin, Redfield, and Wirth. Unlike other social sciences, symbolic interactionism emphasizes greatly on the ideas of action instead of culture, class and power. According to behaviorism, Darwinism, pragmatism, as well as Max Weber, action theory contributed significantly to the formation of social interactionism as a theoretical perspective in communication studies.