Veteran actor Gary Sinise joined the cast of 13 Reasons Why season 4 as Clay's therapist Dr. Robert Ellman. Clay's rapidly declining mental health is a large focus of the final season of the Netflix show, so Clay and Dr. Ellman spend quite a bit of time together over the course of 13 Reasons Why season 4.
The final season of 13 Reasons Why follows Clay and his classmates as they navigate their finale year at Liberty High. Clay is still reeling from the events of the previous year - the murder of Bryce Walker and the subsequent death of Monty de la Cruz in prison, after he was framed for Bryce's murder. Clay's guilt and stress over carrying the knowledge of Bryce's true killer and his involvement in framing Monty cause him to have severe panic attacks. He visits Dr. Ellman to work through his personal traumas.
Clay's sessions with Dr. Ellman serve as narrative device for 13 Reasons Why season 4. Clay recounts important events in their time together, and Dr. Ellman's pushback allows Clay to have breakthroughs that propel major events of the season. The therapist ends up being a crucial aspect of 13 Reasons Why season 4, so it only makes sense to have a well-known actor such as Sinise portray the character.
The younger sect of the 13 Reasons Why audience may not recognize Gary Sinise, but he's had a number of starring roles on the big and small screen during his career. Sinise played Mac Taylor on the long-running crime drama CSI: NY. He appeared in every episode of the series, as his character headed up the CSI team. Sinise has also had a number of prominent film roles over the years. He starred as George in the 1992 adaptation of John Steinbeck's novel Of Mice and Men. But Sinise's most iconic movie character would probably be Lieutenant Dan Taylor in Forrest Gump. Lieutenant Dan was the eccentric commanding officer and friend to Tom Hanks' Forrest. The role left such a mark on Sinise that he formed a cover band in 2004 named after the character.
As Dr. Ellman was a vital character in 13 Reasons Why season 4, a commanding presence was needed to bring that character to life. The therapist provided the tough love that Clay needed to begin his journey to healing to live a happier and healthier life in college. As he's well known for playing characters like an army lieutenant and a detective, Sinise was able to bring that same energy to the gruff and gentle therapist. Sinise's touch provided the perfect ending note to Clay's story on 13 Reasons Why.