The Blue Avians allegedly are a higher-dimensional humanoid species with avian features. They are said to be 8 feet tall, with blue skin that is partly covered with feathers, and they have a small beak instead of a regular nose and mouth.
They would live in planetoids that they refer to as spheres. They would be among the prominent members of an alleged Sphere Being Alliance, which may or may not be part of a so-called Secret Space Program Alliance.
There does not seem to be a lot of reliable or verifiable information about them, and they were never mentioned or encountered until allegedly some years ago, even though they allegedly have been assisting humankind for millions of years.
On a personal note, in all of my years of working with contactees I have only come across one person who claims to have encountered them, but that was after reading material about them, which makes me think this was more likely an implanted image. (Greys, the Praying Mantis like beings and Reptilians all have the reputation of being able to choose how they appear to us.