He had charisma, but he also had an edge which made his good guys human and his villains impulsive and unpredictable. On screen he was hard to ignore and could have easily played many of the roles that made Robert Redford or Dennis Hopper famous.
Unfortunately, John Drew Barrymore also had a history of drug and alcohol abuse and developed a difficult reputation which derailed his promising career. Many of his guest staring roles on Rawhide, Gunsmoke and other popular shows of the time are available on DVD collections and are well worth seeking out, not only for his wonderful performances, but also for a peak at the quality of the acting and writing that took place in the early days of television.
To stumble upon the work of John Drew Barrymore is like discovering a rare baseball card from and era long gone. And anyone familiar with his work will understand why he's the pick of the day for Not Very Famous...but should be.