Introduction
Brahma is the creator among the major gods. In the Ramayana he plays a part at several key points: he grants Ravana his boon, inspires Valmiki to compose the epic, and gives weapons.
The boons
Brahma granted Ravana, Kumbhakarna and Vibhishana the boons that shaped the story. He also gave Indrajit boons, and the Brahma weapon (Brahmastra) is named after him.
The poet
Brahma appeared to Valmiki after he spoke the first verse and told him to compose the story of Rama.
In Lanka
At the end of the war, Brahma was among the gods who appeared before Rama and Sita after the trial by fire.