Tressym are a species of magical beasts resembling housecats with feathered wings, native to Dungeons & Dragons. Having debuted in the Forgotten Realms, they are characterized by their intelligence, immunity to poison, and ability to detect both poison and invisible creatures, and are popular choices of familiars for wizards of good alignment, especially human and elf ones.
Al-Qadim is home to a distant relative of the Tressym known as the Winged Cat. This species of flying feline lacks the magically keen senses and poison immunity of the Tressym, and is divided into two subspecies; the "Lesser Winged Cat", or Jana-qitat (also known as the "fluttercat"), most closely resembles the tressym in appearance, but is far less intelligent (in AD&D: Average Int 2-4 compared to the tressym's Average Int 11-12), whilst the "Greater Winged Cat", or Jana-nimr, is a giant version that is 6-7 feet long! It's much smarter than its jana-qitat cousin, but still not as smart as the tressym (Average Int 8-10), and like the tressym has its own language, with about 10% able to speak the langauge of sphinxes or other catlike creatures.
The tressym first debuted in Advanced Dungeons & Dragons 2nd edition, in the adventure "Haunted Halls of Eveningstar".