Garo are a new member of the ghost monster class, added in dNetHack, as well as Slash'EM Extended and SLASHTHEM. To differentiate between different members of this class, the ASCII tile for the class has been changed to . (a period).
"That is the ghost of a ninja. Its scientific name is Garo
Robe. They are merely shells that are empty on the inside.
They're the shells of spies from an enemy nation sent to
investigate Ikana. They have been unable to forget their
living days. Even now their spirits--emptiness cloaked in
darkness--continue to spy."
Leader of the ninja that came from points unknown to spy on
the Kingdom of Ikana. This master spy has uncovered secrets
greater and more dangerous than those found by lesser garo.
Garo come from the Legend of Zelda series. They are opponents in Majora's Mask.
dNetHack Makemon.c line 1045