According to Sri Lankan Buddhism, Gurr (or Gurulu) is an evil and carnivorous giant eagle that feeds on flesh. It is widely believed that Gurr is a demonization of the Hindu lesser deity Garuda as Sri Lankan Buddhism and Hinduism have been at odds in the past.
"A demon that takes the shape of a giant bird in Sri Lankan mythology. It is said that it may have been a corruption of Garuda."
—Shin Megami Tensei III: Nocturne Compendium
Gurr can only be fused through Sacrificial Fusion if said fusion results in a Sparna and if a Tyrant Demon is used as the Sacrifice.
Shin Megami Tensei IMAGINE
Gurr acts as one of the two law field bosses tied to the Invoke system and will appear in Shinagawa once every hour during weeks when the Law alignment dominates the system. After obtaining the rare black eagle ornament he drops, he can be fused by a special double-fusion of Garuda and Rakshasa.
Shin Megami Tensei: Strange Journey
"A demon that takes the shape of a giant bird in Sri Lankan lore. It is thought to be a derivation of Garuda."
—Shin Megami Tensei: Strange Journey Compendium
Gurr appears as a recruitable demon in Sector Fornax. A wounded, moribund Gurr is seen and spoken to in Jack's Squad HQ.
High chance of countering Physical attacks with Heavy damage
Gallery
Gurr as he appears in Persona 3
Gurr as seen in Soul Hackers.
Gurr as he appears in Shin Megami Tensei: IMAGINE
Gurr in Last Bible III
Gurr as he appears in Shin Megami Tensei III: Nocturne.
Gurr Yaksha as it appears in Giten Megami Tensei
Gurr as it appears in Shin Megami Tensei Trading Card: Card Summoner
Trivia
Gurr's 3D model differs significantly from his artwork in Persona 3 and 4. While they are the same basic shape, many details are different, with only the head matching. This is due to Gurr's artwork being based on the one from Devil Summoner: Soul Hackers, while his 3D model is instead based on his appearance in Shin Megami Tensei III: Nocturne.