The Glinean Raven is a much sought after battle pet, even though it is really easy to obtain. The problem is that only worgen players can get this, so this leaves most people out of being able to get it. However, if you get it on any worgen character, any character can use it, even horde players.
To get the Glinean Raven you need to visit a Battle Pet trainer with a worgen, and these are found in Goldshire, Stormwind, Dolanaar and Darkshore.
If you don't already have a worgen, the fastest way to get this is by creating a worgen Death Knight. The quest line to be "released" from the non-optinal quests are a lot faster than those from the worgen starter zone, and once you have finished the DK starting quests you will be teleported to Stormwind, so you don't even need to travel any further to get the pet.
It is not required to keep the worgen after you have learned the pet, so feel free to delete it.
Some people have tried to make this faster by summoning low level worgens to Stormwind, but you need to complete the introductory quests to be able to interact with the Pet Battle Trainer.