Professor D'artagnan (プロフェッサー・ダルタニアン Purofessā Darutanian or ダルタニアン教授 Darutanian-kyōju), is a professor at a university in England with Seitaro Takamine. Despite appearing as a serious-looking man (and he is a serious guy), D'artagnan has a habit of disguising or cosplaying in odd costumes.
He was first introduced wearing a sea bass costume while smoking a cigar when Kiyo bursts in to his office. He tells Kiyo to forget what he saw. He is later seen in a fairy costume saving Zatch from snakes saying he is the spirit of the forest and investigating the explosion that happened in the forest six months ago. He is later seen in a helping Seitaro with the stone tablets.
He appears in later episodes of the anime, wearing outfits based on other people's clothing regardless of their age or gender and acts into their persona.
Professor D'artagnan serves as the main antagonist of 00F ~Ōgon no Chichi wo Motsu Otoko~ (lit. "00F - The Man with the Golden Breast"), a non-canon original video animation by Toei Animation. He acts as the leader of a group of thieves that steal other people's breasts known as the Boing Thieves (ボイン盗賊 Boin Tōzoku). Known members of his group are Hiroshi Yamanaka, Kane, and Mamoru Iwashima. He also mind-controlled Agent 00G Zatch Bell and Agent 00K Kiyo Takamine to his side until the mind controlling device was removed from their head.
Professor D'artagnan later engages battle with Agent 00F Parco Folgore with Lady Susan's breast equipped to his chest and uses it for combat. D'artagnan is also wearing his fairy costume and a pumpkin helmet during the battle. D'artagnan gains the upper hand most of the time in the battle but is ultimately defeated. After his defeat, D'artagnan makes one final stand and launch giant breast missiles, filled with stolen breasts, into the sky. However, once again, Agent 00F saves the day and D'artagnan flees.
A list of combat techniques D'artagnan used in the OVA while equipped with Lady Susan's breast.