Arnold is a Rottweiler dog, who appears as a supporting, but popular, background character in the HBO series Entourage and the follow-up Entourage (2015). He is portrayed by canine actor Rocky.
Arnold and Drama.
On the show’s pilot episode, actor Vincent Chase decides to get a guard dog for his Hollywood mansion to protect him and his entourage from a potential "Charles Manson" attack, despite the skepticism of his manager Eric "E" Murphy, who sees the dog in a photo as a potential "lawsuit". Unknowingly, the guys get a new loyal friend for life.
Via Turtle's contact Black Axe, Arnold is delivered in a cage to Vince and his friends, E, half-brother Johnny 'Drama' Chase and driver Turtle, who thought they were receiving a Rottweiler that was a “vicious attack dog”.
He initially appeared as a hostile one and the boys made Turtle wear a protection suit and released Arnold from his cage to test his skills; Arnold attacked and managed to overpower Turtle as Vince, E and Drama cheer and laugh from the mansion balcony.
Eventually, Arnold turned out to be a laid back, friendly and loving dog, despite his initial aggressiveness, and implied to be a coward, which is seen when he hid behind Turtle during a break-in.
Despite the gang's disappointment, they decided to keep Arnold as a pet anyway and the lovable Rottweiler continues to occasionally make appearances into the show, either hanging out with his owners, sleeping alongside some of them in their respectful beds, lying on the couch in the living room, and also occasionally being used to pick up women at the local park.