The Saddest Death In Yellowstone Season 1

As any "Yellowstone" fan who's been around since the show's early days can tell you, bodies have indeed been piling up with shocking regularity ever since the show premiered. However, the saddest and most heartbreaking death in the series has to be that first one during Season 1.
It came during the pilot episode with the death of Lee Dutton who was killed in a fateful showdown with the Broken Rock Reservation faction. The showdown began over a cattle dispute after several of the Duttons' prized livestock inadvertently wandered onto Broken Rock lands.

Lee’s death was obviously devastating for the Duttons because he was the man in line to take over the Yellowstone Dutton Ranch. But his death heightened the tensions with the Broken Rock crew and threw the future of the ranch into flux by creating a power vacuum that still hasn't been entirely filled.