John Kirby, the acting coach who mentored generations of performers and was the son of character actor Bruce Kirby, died Wednesday at 75. ALS claimed his life three years after his diagnosis.

The younger Kirby built a career behind the scenes, establishing himself as a respected instructor in Los Angeles. He worked with actors navigating the demands of professional performance, drawing on insights gleaned from his father's decades in the industry. Bruce Kirby, known for roles in "Seinfeld" and "All in the Family," passed away in 2014 at age 95.

John Kirby's death marks another loss within Hollywood's teaching community, where acting coaches serve as crucial figures in actors' professional development. The profession often operates outside the spotlight, yet these instructors shape how performers approach their craft. Kirby maintained connections across multiple generations of students, reflecting the long arc of his career as an educator.

ALS, amyotrophic lateral sclerosis, is a progressive neurodegenerative disease that gradually paralyzes muscles while leaving the mind intact. The diagnosis typically comes with a difficult prognosis, yet Kirby continued his work with students during the three years between diagnosis and death. His resilience during illness speaks to the commitment he brought to teaching.

The passing of John Kirby echoes broader conversations within Hollywood about the invisible infrastructure supporting its talent. Acting coaches rarely receive the recognition accorded to actors themselves, yet their influence on performers' careers can prove substantial. Kirby's lineage in the industry, following his father's acting career, created a different path toward impact within entertainment.

His legacy rests with the actors he trained and the methods he imparted to students navigating one of the profession's most competitive landscapes.