Den

Den is a mixed-breed dog whose most notable feature is a metal front leg. She lost her left foreleg in a traffic accident before the series began, and Resembool's automail craft supplied a prosthetic to replace it. Her sex has been a point of confusion: Japanese guidebooks and the Chuang Yi translation confirm her as female, while the VIZ manga and both Funimation dubs treat her as male.

Fierce devotion is Den's defining quality, enough that Pinako has dubbed her the finest guardian in Resembool. She also shows a gentle, caring streak, nuzzling up to comfort Pinako after Winry departs for Rush Valley to train at Atelier Garfiel. Her instincts run sharp as well: the eerie aura surrounding Van Hohenheim unsettles her so badly that she nearly has to be held back from lunging at him.

Den lives out the story as a fixture of the Rockbell home, a small but steady presence through the brothers' comings and goings; Edward once grumbled that she had eaten Alphonse's cake. In the final chapter she is startled and overjoyed to find Alphonse restored to his flesh, barking wildly at the returning brothers. A bonus side story shows her gently carrying off Al's helmet to cradle a family of hatchling birds. Her name traces back to Densuke, a dog once owned by creator Hiromu Arakawa, itself a word for a prized variety of Japanese watermelon.