Cornelius Frederiks (died 16 February 1907) was a leader of the ǃAman (Bethanie Orlam), a subtribe of the Orlam people, in the southern area of German South-West Africa, today's Namibia. He was a rival Kaptein of the Bethanie Orlam, contesting the chieftaincy of Paul Frederiks. Among the Orlam people living in Bethanie, Cornelius had more followers but Paul was the official leader who also had the support of the German colonial powers.
When the Herero and Namaqua War of 1904-1907 broke out, Frederiks was one of the indigenous leaders that actively fought a guerrilla-style war against the Germans. He often sided with Hendrik Witbooi, leader of the ǀKhowesin (Witbooi Orlam), and both were wanted for a 3,000ℛℳ ransom. The German Schutztruppe kept the upper hand in the majority of battles and forced most Nama and Orlam groups to surrender. The group under Frederiks gave up on 3 March 1906.
On 9 September 1906 Cornelius Frederiks was imprisoned at Shark Island concentration camp in Lüderitz as part of a group of 1,795 Nama people. Most of them died in the icy wind due to malnutrition and neglect, their bodies were buried at low tide and soon washed into the ocean. Frederiks died on 16 February 1907. He was decapitated and his head was sent to Germany for research on racial superiority. Eugen Fischer's study on "racial anatomy of 17 Hottentot heads" appeared in 1922.
- Dierks, Klaus. "Biographies of Namibian Personalities, F". Retrieved 9 March 2012.
- Booysen, Dani (10 August 2004). "Die pad na Ohamakari" [The road to Ohamakari]. Die Republikein (in Afrikaans).
- Silvester, Jeremy; Erichsen, Casper. "Luderitz's forgotten Concentration camp". The Cardboard Box. Retrieved 9 March 2012.
- Mashuna, Timotheus (9 March 2012). "Cornelius Frederiks: 'The Most Dangerous Enemy of the German Imperial Forces'". New Era. Picture of Cornelius Frederiks at Shark Island