John “Duke” Wayne was a popular Hollywood icon who starred in many Westerns, most famously for movies like Stagecoach in 1939 and True Grit in 1969. His acting and directing career spanned 40 years and is considered Hollywood royalty.
John had seven children, including a daughter named Mary Antonia, who married Donald LaCava. The couple had eight kids together, including Brendan.
In 2011, Brendan was cast in a Jon Favreau-directed film, Cowboys & Aliens, which brought him into the limelight. Even though he was nowhere near top-billed, his relation to John Wayne, as well as his good looks, brought quite a bit of press to the relatively green actor.
While Brendan’s grandfather passed away in 1979, only seven years after Brendan was born, he still has some early memories of John, or “granddaddy,” as he recalls.
Source : https://www.distractify.com/p/is-brendan-wayne-related-to-john-wayne