In the anime adaptation of The Three Musketeers, often known as Dogtanian and the Three Musketeers, the character of Athos is reimagined with a unique visual design, most notably as an anthropomorphic dog of a large breed, resembling a Mastiff or a Smooth-coated St. Bernard. His imposing stature and immense physical strength distinguish him within the group, as he is frequently portrayed as the most powerful of the three musketeers, a fighter capable of overwhelming his enemies with raw power, sometimes even rendering his sword unnecessary.

Athos possesses a complex personality that blends vanity and gluttony with a generally amiable disposition, though he has a notable temper, particularly when his drink is spilled or interrupted. His relationship with alcohol, while a significant trait, is handled with less of the tragic, darker undertones found in the original novel; the anime adaptation streamlines this aspect, including his backstory regarding the villainous Milady de Winter. The tragic marriage to Milady, which is a cornerstone of his character in other versions, is simplified for the animated narrative. Despite these lighter touches, he retains a pragmatic and cynical edge, a wounded soldier betrayed by a past lover, which has contributed to his dependence on alcohol during periods of inactivity.

Within the story, Athos serves as the strongest member of the trio, earning widespread respect across Paris for his combat prowess. He forms a close and steadfast partnership with the protagonist, Dogtanian, and together with his loyal comrades Porthos and Aramis, he embarks on missions to thwart the plots of Cardinal Richelieu, rescue Juliette, retrieve royal jewels, and secure peace between nations. His bonds with Porthos and Aramis are defined by an unwavering loyalty, embodying the famous creed of "One for All and All for One". In the sequel series, The Return of Dogtanian, which takes place a decade later, Athos undergoes a significant transformation. His role shifts away from that of a formidable combatant into one focused on comic relief, characterized by exaggerated clumsiness and slapstick routines.

Regarding his abilities, Athos is a highly skilled and disciplined soldier. While his combat style leans heavily on his immense strength, he is also a veteran tactician and a natural leader with a sharp intellect. He is proficient with firearms and is often considered the finest swordsman among the musketeers. Despite his prowess, in some adaptations he is depicted as less skilled with a pistol than Aramis and less specialized in melee combat than Porthos, though these distinctions are balanced by his overall strategic mind and leadership qualities. He is a man of his word, known for his loyalty and his ability to guide his allies with a mixture of sarcasm and bleak humor, serving as the pragmatic and cynical conscience of the group.