There are many clinical psychologists who have been famous for groundbreaking theories that they have developed. Many are from modern times, and continue to make a major impact on the world of psychology, especially among Clinical Psychology Masters students.

1. Margaret Thaler Singer (1921-2003) – Singer was very famous for her work with cult members. She studied the effects of brainwashing among American POWs from the Korean War at Walter Reed Institute of Research. Singer testified at the trial of Patricia Hearst in 1976, and also interviewed Peoples Temple survivors. She was nominated for the Nobel Prize twice. In addition to cults, she was an expert on family therapy and schizophrenia.
2. Albert Ellis (1913-2007) – Ellis was the founder of many popular cognitive-behavioral therapies that are still used today. He is most famous for developing the Rational Emotive Behavioral Therapy (REBT) method. Ellis published several works while still in school, including a critique of personality tests popular during the 1940′s. His REBT method focuses on correcting beliefs that contribute to emotional distress. Ellis founded The Institute for Rational Living 1959, an institute based on his theories.
3. Erik Erikson (1902-1994) – Erikson was very well-known for his work on human social development. He originally used the term “identity crisis”. Erikson elaborated on Freud’s 5 stages of development by adding 3 new stages. He placed an emphasis on the relation between a child’s living environment and development. Erikson was also one of the first psychologists to advocate the ego having an important role.
4.  Albert Bandura (1925- ) – Bandura has stressed how observation and imitation have a role in development. His best-known experiment involved the Bubo Doll study in 1961, when children were believed to have hit the doll after observing a woman doing the same thing. He was one of the first to prove that behavior is not always reward or punishment-related. Bandura has stated that he does not see himself as a behaviorist. Early studies on aggression in adolescents helped promote his interest in observational learning.
5.  B.F. Skinner (1904-1990) – Skinner was known for achievements in behavioral theories. He carried out some of his most successful experiments using his own inventions. Skinner was an early leader in behaviorism, with an emphasis on operant conditioning and schedules of reinforcement. His cumulative recorder device helped build on Pavlov and Watson’s earlier work. Skinner was known for creating the “Skinner Box”, where rats learned to press levers for treats. He also created a special heated crib when his wife asked for an alternative to conventional cribs.
6.  Mary Ainsworth (1913-1999) – Ainsworth was well-noted for her work on how children related to caregivers. She studied mother-child attachments in both Uganda and England. Ainsworth first conducted the “Strange Situation” assessment at John Hopkins. Several studies have been influenced by her initial work.
7.  Hans Eysenck (1916-1997) – Eysenck is one of the most-quoted psychologists in modern publications. Eysenck was a critic of psychotherapy, which was a controversial position in earlier years. He believed that intelligence was often hereditary. Eysenck also played a role in developing clinical training approaches.
8.  Leon Festinger (1919-1989) – Festinger was famous for developing two of the most well-known theories in psychology. His most famous theory was known as cognitive dissonance, which occurs when people experience problems with their behaviors and beliefs not matching. Festinger also emphasized the social comparison theory, in which people compare their beliefs and attitudes to those of others for greater self-awareness
9. Phil McGraw (1950- ) – McGraw is a well-known psychologist with his own TV show. He is very famous for addressing many of the social issues common in society today, including bullying and addiction. McGraw’s well-known methods have allowed many people to seek help who would not have done so otherwise.
10. Elizabeth Loftus (1944- ) – Loftus has studied human memory extensively, including the effects of false memories. She developed and successfully tested the theory that false memories can be created. Loftus was involved in several high-profile trials, including those of Ted Bundy and O.J. Simpson.

References:

• http://www.factnet.org/Margaret_Thaler_Singer/Margaret_Singer.html
• http://www.psychologistanywhereanytime.com/famous_psychologist_and_psychologists/psychologist_famous_albert_ellis.htm
• http://www.psychologistanywhereanytime.com/famous_psychologist_and_psychologists/psychologist_famous_erik_erikson.htm
• http://psychology.about.com/od/profilesofmajorthinkers/p/bio_bandura.htm
• http://psychology.about.com/od/profilesofmajorthinkers/p/bio_skinner.htm
• http://psychology.about.com/od/profilesal/p/ainsworth.htm
• http://psychology.about.com/od/profilesal/p/hans-eysenck.htm
• http://www.drphil.com/shows/page/bio/
• http://en.wikipedia.org/wiki/Elizabeth_Loftus