This paper aims at introducing a recent trend of what has been called the posthuman, or posthumanism. Since science and technology brought almost unprecedented achievements to human society for the last few decades, there have been a number of efforts to reconsider the knowledge and beliefs that we have had about humanity. The posthuman refers to re-creating the human after humanism that the modern has established a long while, while posthumanism comprises the attempts to define the changes of humanity that can`t be explained any longer with previous criteria and further to radically reorient a relationship between human and non-human. The so-called `New Materialisms` and `Thing Theory` are new entries in the field of posthumanism. Examining at first the issues and problematics of posthumanism especially in relation to transhumanism and critical posthumanism, this study brings major tenets of new materialisms and thing theory to light. To deliver this purpose less formally, it both starts and ends with brief comments on well-known American novels that representatively articulate the environments of the posthuman.