Defender of the Citadel
From A Wiki of Ice and Fire
Defender of the Citadel is one of the hereditary titles held by the head of House Hightower. The Citadel, the center of the order of maesters, was established on a tract of land granted by King Urrigon Hightower and ever since, House Hightower has been a patron of the order.
Lord Leyton Hightower is the current possessor of the title.[1]