Which main male character in The Big Bang Theory lacks a Ph.D.?

Howard Wolowitz is the main male character in The Big Bang Theory who lacks a Ph.D.

Howard is an aerospace engineer with a master’s degree from MIT, making him academically accomplished even though he does not hold a doctorate. His engineering background also distinguishes him from Sheldon, Leonard and Raj, whose careers are presented primarily through physics and astrophysics research.

The absence of a Ph.D. becomes a recurring source of jokes. Sheldon often treats Howard as less intellectually impressive and calls attention to the difference between “Doctor” and “Mister.” Howard pushes back by emphasizing that his engineering work has practical results, including equipment designed for NASA missions and the International Space Station.

Howard’s education is sometimes confused with his professional status. He is not uneducated or merely an amateur; his MIT master’s degree qualifies him for advanced aerospace work. He also becomes an astronaut and travels to the International Space Station, but that achievement does not change the show’s established fact that he is the one among the four central male scientists without a Ph.D.