Bill Bixby, as Dr. David Banner, brought a sense of vulnerability and likability to the role. His character's struggles to control his transformations and lead a normal life made him relatable to audiences. Bixby's chemistry with co-star Lou Ferrigno, who played the Hulk, was essential to the show's success. Ferrigno, a former professional football player and bodybuilder, was cast for his impressive physique and ability to convey emotion through body language.