"Gentle Giant" was a nickname associated with Don Williams, but the FACTS provided do not include a single most-cited work — no album title, song title, or specific release appears in the list. Following the Evidence Lock rule, I cannot invent or import any titles from training data.

Given the thin FACTS, here is a shortened biography that stays strictly within what the evidence supports:

Don Williams was a country music singer-songwriter and guitarist, born on May 27, 1939, in Floydada, Texas. He was a citizen of the United States who worked across the occupations of singer, songwriter, musician, and guitarist throughout his career in the country music genre.

Williams was born in Floydada and died on September 8, 2017, in Mobile. His career as a country music performer placed him among those practitioners of the genre working during the latter half of the twentieth century and into the twenty-first.

The Library of Congress catalogued him under the authorized label "Williams, Don, 1939-2017," a designation that marks the span of his life from his birth in Floydada through his death in Mobile at the age of seventy-eight.