Skyhead
The Skyheads were beings from another dimension which resembled giant baby heads. They could fly through the air, generating a vortex slipstream in order to reach high speeds. The Skyheads used violently powerful gusts of air to attack.
Unable to communicate effectively with Colonel Lafayette, they launched an attack on London, killing civilians, reporters and UNIT personnel. After an incarnation of the Master posing as the Doctor hypnotised them into helping humanity, they collaborated with UNIT during the ongoing crisis involving interdimensional invasions. (AUDIO: UNIT Dominion)
Behind the scenes
The sound of the Skyheads came from a slowed down version of baby noises.