grand old man

plural grand old men

1. A male leading light; a man who is the most senior exponent of a particular field.

   Cervantes's Quixote made him the grand old man of belles-lettres.

   2 more examples

   Lope K. Santos, the "grand old man" of Tagalog letters, had long ago deplored the mechanical goodyism of the reading material […]

   1974, Epifanio San Juan, Introduction to Modern Pilipino Literature, page 94

   We were fortunate to be accompanied by another member of Terramar, Volkmar Vareschi, a German-born Venezuelan now in his 80s who is a superb artist and the country's grand old man of tropical ecology.

   1989 May, Uwe George, “Venezuela's Islands in Time”, in National Geographic, volume 175, number 5, page 545