At its core, CBS cop drama “Blue Bloods” revolves around the Reagan family. Only five actors have been in every episode of “Blue Bloods,” a list that consists of the principal adult Reagans, each of whom works or worked in a branch of New York City law enforcement. That said, because the show follows its unretired main characters in their distinct personal lives as well as at their workplaces, rounding out the series’ cast requires a sizable contingent of supporting actors and guest stars.
As a result of this maximalist approach to storytelling, the show’s contributors come from a wide range of backgrounds. For example, the “Blue Bloods” cast includes more Broadway actors than most viewers unfamiliar with the world of theater likely realize. Of course, some outright famous celebrities have contributed to the show over its lengthy run too. With that in mind, here are five of the most famous actors that have significantly impacted “Blue Bloods” through the limited scope of a guest star role.
Dylan Walsh is Blue Blood’s narcissistic NYC mayor
Perhaps the role that has defined Dylan Walsh’s acting career more than any other is his portrayal of series co-lead Dr. Sean McNamara in all 100 episodes of FX’s drama “Nip/Tuck.” He also co-starred in the 1995 Michael Crichton book adaptation “Congo” and, in 2021, became a recurring cast member on “Superman & Lois.”
Starting in “Blue Bloods” Season 10 and continuing sporadically since then, Walsh plays New York City mayor Peter Chase. When viewers first meet him in Season 10, Episode 8, he presents himself as an ally to Erin Reagan (Bridget Moynahan), claiming that he’ll endorse her budding campaign for District Attorney. Erin, however, soon learns that he made the same offer to her competition as well. As it turns out, he’s merely looking for a lackey rather than the best person for the District Attorney position. From that point on, Mayor Chase remains a strict opportunist and someone with whom the Reagan family must negotiate on more than one occasion over the course of his 12 appearances.
Mayor Chase’s opportunism is so polarizing, one user on the “Blue Bloods” subreddit started a thread dedicated entirely to the fact that he’s the only character they truly hate. While his character may be plenty unlikable, his evocation of such strong feelings in viewers makes it clear Walsh is doing his job well as a part of the “Blue Bloods” cast.
Ed Asner made the most of his one episode appearance
When Ed Asner died in 2021, his admirers began looking back on his body of work with the sort of reverence reserved for legends, and rightfully so. Among his hundreds of credits were key roles in films and TV shows like “The Mary Tyler Moore Show,” “JFK,” “Elf,” and “Up.” Asner remained active in Hollywood for the majority of his life, eventually showing up in “Blue Bloods” Season 10, Episode 15, which premiered during what would turn out to be his twilight years in 2020.
Asner plays a character named Chuck Kennedy in this single episode. After an assailant breaks into his home and steals one of his prized possessions, he calls up his old friend Frank Reagan (Tom Selleck) for help. Frank then reveals that Chuck, whom he calls Mr. K, was an instrumental figure in his childhood and ultimately helped set him on the career trajectory that would come to define his adult years.
Of course, given Asner’s advanced age at the time of this appearance, his role is somewhat limited. Nevertheless, the fact that he turns out to be a friend and mentor to Frank imbues the character with an aura of importance befitting Asner’s historic filmography.
Lou Diamond Phillips was an unlikely ally of Danny Reagan’s
After just a few prior acting appearances, Lou Diamond Phillips broke out in Hollywood for his portrayal of real-life rock star Ritchie Valens in the 1987 biopic “La Bamba.” Over the course of the ensuing decades, he has starred in films like “Stand and Deliver,” “Courage Under Fire,” and “The Big Hit,” as well as TV shows including “Longmire” and “Prodigal Son.”
In “Blue Bloods” Season 9, Episode 1, Phillips debuts as a drug cartel boss named Louis Delgado. Danny Reagan (Donnie Wahlberg) already has a history with the cartel at this point in time, having confiscated some cartel funds in Season 7. In retaliation, a mob member burns down his house in the Season 7 finale. In Season 9, Episode 1, Danny pursues Delgado as his principal arson suspect. Because Danny can’t take on this case without some considerable bias, however, he brings Delgado to trial with insufficient evidence. Then he essentially arranges for him to be killed.
Phillips, however, returns for three more episodes of “Blue Bloods,” culminating with Season 10, Episode 12. By this point, Danny and Delgado have become unlikely allies of sorts, even if Delgado is now in jail. One component of his role fans took to in particular is what appears to be a reference to Phillips’ character on “Brooklyn Nine-Nine,” creating an unexpected but somehow fitting link between CBS’ cop drama and the NYPD cop comedy.
Danny Trejo brought instant believability to his role
Actor, restauranteur, and general pop culture icon Danny Trejo appears in “Blue Bloods” Season 9, Episode 19, adding to an impressive filmography consisting of roles in more than 400 films and TV shows. In 2019 alone, when his “Blue Bloods” episode first aired, Trejo cameoed in episodes of “Young Justice,” “American Dad,” “What We Do in the Shadows,” “The Flash,” “Family Guy,” and more than a dozen additional projects.
On “Blue Bloods,” Trejo plays cartel leader Jose Rojas, who becomes the primary suspect for the murder of Louis Delgado’s wife. Delgado collaborates with the NYPD to apprehend Rojas, but the cartel leader quickly catches on to their plan. During the ensuing shootout, tensions come to a head as Delgado openly wishes for the death of his wife’s murderer, while Danny opts instead to take the man in alive.
This is about the extent of Trejo’s “Blue Bloods” role. But, like Ed Asner’s brief appearance, his real-life celebrity lends his character’s overall limited screen time some extra oomph, imbuing Rojas with an importance befitting of his role as a cartel bigwig.
Treat Williams could still impact Blue Bloods, even after his death
By the time Treat Williams died in June of 2023, he had become famous for his decades of acting work, including important roles in “Hair,” “Once Upon a Time in America,” “Dead Heat,” and a televised adaptation of “A Streetcar Named Desire.” In Season 6, Episode 11, Williams joins the “Blue Bloods” cast as an NYPD detective named Lenny Ross. When Frank Reagan was an active NYPD detective, prior to landing his position as Police Commissioner, he and Lenny were partners. Now, however, whenever Lenny resurfaces in Frank’s life, it’s typically a cause for drama. In Season 6, Episode 11, for example, Lenny is about to publish a memoir, and Frank is worried about how his past deeds detailed in the book will come across. Meanwhile, in his final appearance, which takes place in Season 13, Episode 20, Lenny is reluctant to reveal that he was diagnosed with cancer.
After Williams’ death, “Blue Bloods” fans openly shared their appreciation for his six-episode run. “Sure loved his appearances on this show. What a shame,” wrote u/Kairenne in a thread on the “Blue Bloods” subreddit, in one of numerous comments praising his body of work.
Although Lenny’s character met a sudden and unexpected end, some Reddit users think his character’s ensuing storyline could inspire Frank to retire, raising the possibility that he might still impact “Blue Bloods” even in the wake of what is definitively Williams’ final appearance.
