Roy Frederick Baumeister is an American social psychologist who is known for his work on the self, social rejection, belongingness, sexuality and sex differences, self-control, self-esteem, self-defeating behaviors, motivation, aggression, consciousness, and free will.

Social rejection occurs when an individual is deliberately excluded from a social relationship or social interaction. The topic includes interpersonal rejection, romantic rejection, and familial estrangement. A person can be rejected or shunned by individuals or an entire group of people. Furthermore, rejection can be either active by bullying, teasing, or ridiculing, or passive by ignoring a person, or giving the "silent treatment". The experience of being rejected is subjective for the recipient, and it can be perceived when it is not actually present. The word "ostracism" is also commonly used to denote a process of social exclusion.