Appearing in the pilot episode "Woo-oo!," the Headless Man-Horse was initially dormant within his saddle at McDuck Manor until he was summoned when Louie unknowingly sat on the saddle. He then teamed up with Captain Peghook as his steed with the Deus Excalibur as their weapon against the children, until Scrooge McDuck shows up to take them head-on. Scrooge exploits Peghook's demand for his head by tricking the captain into chopping off a statue's head, causing the captain to disappear, while the Headless Man-Horse receives the head. Grateful that he has a head, he thanks Scrooge in Morse code and leaves the manor.
In "The Shadow War!", he aids in fighting the shadow army under threat of being fired. He and Lil Bulb are surrounded by shadows and are saved by Fenton.
In "The 87 Cent Solution!", he appears in a casket pretending to be Scrooge with his bust painted so that it would look like the real Scrooge in order to trick Flintheart Glomgold into thinking that Scrooge is dead so he can get Glomgold to confess to his crime.
Manny appears in issue #8 of the series. Taking place before his appearance in "Beware the B.U.D.D.Y. System!", Scrooge hires Manny as his fill-in for advisory business meetings after Manny was declared redeemed by Scrooge. Scrooge intended to have his absence re-affirm his authority over his advisors, but the advisors take a liking to Manny. However, Manny ends up indulging in Scrooge's money and resources behind his back. Scrooge confronts the horse and has to fire him after Manny puts up a fight until Bradford Buzzard knocks Manny out. Afterwards, Manny is sent back to the Rehabilitation program.