Michael Hofstadter is the younger brother of Leonard Hofstadter and their sister. He is a tenured law professor at Harvard University. His mother, Beverly, mentioned him to Howard Wolowitz when she visited ("The Maternal Capacitance"). She describes him as being more successful than Leonard.

Leonard has said that Michael is eight inches taller than him because of the nurturing and attention he received from their mother.

He was stated to have been engaged in "The Maternal Congruence" to a NJ judge.

In "The Pants Alternative", it is revealed that when Leonard was young he had to give back a ribbon he won for an experiment seeing if Lima beans grew better with classical music. His mother pointed out his younger brother Michael did a Lima beans growing worse with rock ‘n’ roll music experiment already.

In "The Maternal Combustion", Beverly says that Michael recently argued a case before the Supreme Court.

In "The Spock Resonance", Leonard reveals that Michael was mean to him.

In "The Celebration Experimentation", Beverly mentions that Sheldon and both Leonard's brother and sister were invited to the celebration of her 60th birthday. Leonard didn't even know about it.

He was mentioned by Beverly in "The Explosion Implosion" that of all of her children's spouses, Penny was her favorite. This implies that Michael is now married, obviously to the New Jersey judge.

In "The Celebration Reverberation", he sends Leonard his Christmas letter and telling about all his accomplishments, including building a hospital in Rwanda. This causes Leonard to spiral about his own lack of accomplishments.