Charles Rudolph Boysen (July 14, 1895 – November 25, 1950) was the California horticulturist who created the boysenberry, a hybrid between several varieties of blackberries, raspberries, and loganberries.  
Rudolph Boysen had experimented with various berry crosses in Napa, California during the 1920s. When Boysen first moved to Orange County, he brought berry vines with him which he planted on his in-law’s farm in Anaheim. Boysen worked as Anaheim City Parks superintendent from 1921-1950. In 1923, his hybrid grafted successfully and grew to bear fruit. However, unable to make his new berry a commercial success, Boysen abandoned his crop after breaking his back in an accident. In 1927, he took specimens to Coolidge Rare Plant Nursery in Altadena.  Years later, a fellow grower named Walter Knott heard about the berry and tracked down Boysen. Walter Knott was able to bring a few dying vines back to life at his farm, now known as Knott's Berry Farm in Buena Park, California. Knott named the fruit after Boysen.   
In 1930, Charles Rudolph Boysen was married to Margaret Bruton (1892-1970). They were the parents of Robert Matt Boysen (1924-1980). 
There's a Boysenberry Lane in Placentia, California and a Boysen Avenue in Anaheim, California, both named for Rudolph Boysen. Boysen Park, a 24-acre (97,000 m2) public park in Anaheim, was named in his honor. It features playgrounds, baseball diamonds, a large lawn, and a stucco-coated, Korean War-vintage Navy jet as a children's climbing toy. The Anaheim Tennis Center is located adjacent to Boysen Park, located at 951 S. State College Blvd. Rudolph Boysen died at the age of 55, and is interred at the Melrose Abbey Cemetery in Anaheim.
- "Charles Rudolph Boysen". Soylent Communications. 2014. Retrieved December 30, 2015.
- Natalie Wiser-Orozco, (March 27, 2014). "The History of the Boysenberry". WordPress. Retrieved December 30, 2015.
- Boysenberry Creator's Juicy Details" (Orange Coast Magazine , Nov 2006, pp 208-12)
- Boysenberry (Oregon Raspberry and Blackberry Commission)
- Knott's Berry Farm Historical Background
- Peter B. Flint (December 5, 1981). "Walter Knott of Knott's Berry Farm". The New York Times. Retrieved December 30, 2015.
-  Anahein Public Library
- "Boysen Park". City of Anaheim. Retrieved December 30, 2015.
- How Orange County's places got their tags (Orange County Register. January 25, 2007)