Blocker was born Bobby Dan Davis Blocker[1] in De Kalb in Bowie County in northeastern Texas, son of Ora Shack Blocker (1895–1960) and his wife Mary Davis Blocker (1901–1998). The family moved to O'Donnell, south of Lubbock in West Texas, where they operated a store.

The former Blocker Store is now an abandoned building in downtownO'Donnell, Texas.

He attended Texas Military Institute and in 1946 played football at Baptist-affiliated Hardin-Simmons University in Abilene, Texas. He graduated fromSul Ross State Teacher's College in Alpine, where he earned a master's degree in the dramatic arts. (Although the "Hoss" character on Bonanza was conceived as lovable but slow-witted, Blocker was the only cast member with a graduate degree.)

Blocker was a high school English and drama teacher in Sonora, Texas, a sixth grade teacher and coach at Eddy Elementary School in Carlsbad,New Mexico and a finally a teacher in California. He had worked as a rodeo performer and as a bouncer in a beer bar while a student. He is remembered from his school days for his size of 6 feet 3 inches (18.3 hands) and weight of 300 pounds (136 kilograms; 21 stone 6 pounds), and for being good-natured despite his intimidating size.

Blocker was drafted into the United States Army during the Korean War. He served as an Infantry sergeant in F Company, 2nd Battalion, 179th Infantry Regiment, 45th infantry Division in Korea, December 1951 to August 1952. He received a Purple Heart for wounds in combat according to the June/July 2013 issue of VFW Magazine

In 1957, Blocker appeared in a Three Stooges short, Outer Space Jitters, having portrayed the part of "The Goon," billed as "Don Blocker". Dan Blocker made two appearances on the long running Gunsmoke series: the first on August 25, 1956 in "Alarm at Pleasant Valley," and the second on October 18, 1958 in "Thoroughbreds". He also appeared in 1957 as Will in the episode, "A Time to Die", of the ABC/Warner Brothers western series, Colt .45, starring Wayde Preston.[4]

Blocker was cast in 1957 in episodes of the David Dortort-produced NBC series, The Restless Gun as a blacksmith and as a cattleman planning to take his hard-earned profit to return to his family land in his native Minnesota. That same year, he had at least two roles as a bartender: in an episode of thesyndicated western-themed crime drama Sheriff of Cochise, starring John Bromfield and in the film, Gunsight Ridge. He appeared in the Rifleman. In 1958, he played a prison guard and later had a recurring role as Tiny Budinger in the NBC western series Cimarron City, starring George Montgomery, John Smith, and Audrey Totter. He also was seen in "The Señorita Makes a Choice", a 1958 episode of Walt Disney's Zorro series.

In 1958, Blocker had a supporting role as Sergeant Broderick in "The Dora Gray Story" on NBC's Wagon Train, with Linda Darnell in the title role and Mike Connors as Miles Borden, a corrupt United States Army lieutenant at an isolated western fort.[5] That same year he appeared in "Stagecoach Episode" of the NBC western, Jefferson Drum, starring Jeff Richards.

Blocker was cast as bearded poker-playing rodeo performer, Cloudy Sims, in the 1958 episode "Rodeo" on the David Janssen crime drama, Richard Diamond, Private Detective. In the story line a rodeo performer named Ed Murdock, portrayed by Lee Van Cleef, is murdered before he can make his final performance at the annual event in Madison Square Garden.[6]

In 1959, as Bonanza began its long network run, Blocker guest-starred in an episode of the Keenan Wynn and Bob Mathias NBC series, The Troubleshooters, an adventure program about unusual events surrounding an international construction company. Another 1959 role was as Del Pierce in "Johnny Yuma", the first episode of the ABC western series, The Rebel, starring Nick Adams.

Dan Blocker (1928)