There are only two neutral races currently. Neutral races are races that both major factions can play.
Dragon-like people created by the traitor black dragon Neltherion before he went mad. They were divided by wynms. when the blue dragon Malygoes sent them into a deep sleep, they awoke to the reawakening of the dragon isles, after helping the other wrynms. they traveled to the eastern kingdoms and kalmidor, joining the alliance and horde respectively.
The panda-like pandaren are calm, independent people with the alliance and horde coming to pandaria. Their long feud awakened the sha, forcing the pandaran to take action and join the alliance or horde.
The earthren are a allied race neutral race.
The dwarf like earthren were one of the titan forged, ancient races created by the titan keepers to aid them in their tasks protecting azeroth. Now they have been awakened and are ready to fight the underground war against Xal'tath alongside the alliance or horde.