Artu

Artu (Arthur in the World of Winx series) is Roxy's pet dog.

Appearance
Artu is a tan, Croatian bloodhound (a mix between a Tyrolean bloodhound and an Italian bloodhound). He is tall and slender, and wears a dark red collar with silver studs.

In World of Winx, he retains his coat patterns but his collar is changed to a red collar and has the letter "A" on a silver, square tag.

Personality
Artu is brave, courageous, and loyal. He will do anything to protect Roxy, even if it means getting injured in the process.

Season 4
In "The Last Fairy on Earth", he is seen with Roxy. He was part of the event that helped Roxy obtain her power. Gantlos had severely injured him, which infuriated Roxy, causing something to trigger inside Roxy, causing her to transform. She later used her powers to heal him.

Season 5
In "The Shark's Eye," he is seen with Roxy.

Season 1
In "The Shaman," Artu uses his magical link with Roxy to alert her that the detectives, Evans and Gómez, have just exited their car and heading inside the Frutti Music Bar. Roxy then alerts Bloom of the detectives. Aware that the detectives could put themselves in danger should they continue following Bloom, Roxy has Artu steal the detectives' car keys to keep them distracted for Bloom. The girls laugh as they watch the detectives give chase to try and get their keys back.

He later keeps track of Detective Evans and Gómez as they drive to the airport in hopes of uncovering answers on the mysterious watch they acquired. He is on constant alert and updates Roxy through their magical link. One major incident is when a mysterious cloaked man intercepts the detectives' route and snatches away the watch. From there, Artu focuses on the mysterious cloaked man and when the man reaches a dead end and tries escape, Artu aggressively bears his canines which causes the man to drop the watch, breaking it. But this allows Roxy and Bloom to finally confront the man who reveals his name, Jim, and who had been kidnapping the talents.

Trivia

 * Artu is the abbreviation of the name "Artùro", which is the Italian version of the name Arthur, perhaps as a reference to the Arthurian Legend, as references to the legend of King Arthur have been made many times in Season 4.
 * Artu's name might also be a reference to Star Wars character R2-D2, who is often to referred to as Artoo, similarly to how Marvel Comics character Captain Marvel/Carol Danvers has a pet cat named Chewie after Star Wars character Chewbacca.