Simon was born in Johannesburg, South Africa, the fourth child of Emmanuelle and Phylis Simon. Both of his parents are of Ashkenazi Jewish descent from Poland and Lithuania. From a very young age, Cliff aspired to be the first South African swimmer to win an Olympic Gold medal. His mother, a swimming teacher, taught him from a very young age, and at age 6 he began to show talent as a gymnast. By age 15, Cliff had reached a national level in South Africa in both swimming and gymnastics, but he decided to discontinue training in gymnastics to better focus on swimming.
In 1975, his parents decided to emigrate to the United Kingdom, due to the turmoils in Africa. It was there that Simon completed his schooling and was chosen to swim in the British International squad. He competed in Olympic trials and qualified for the 1984 Summer Olympics in Los Angeles. He was offered scholarships to the University of Houston and Southern Methodist University in Texas, where he trained with the United States swimming team, the Mustangs. This would have culminated in him competing in the 1984 Olympic Games. However, after three years of intense training, he decided to quit and return to South Africa, due to his concerns that he was missing out on his social life.
Back in South Africa, Simon entered the air force where he continued his swimming and achieved the highest athletic award given in the air force, the Victor Ludorum.
In 1982, after serving his two year term in the air force, he landed a job teaching windsurfing and waterskiing at a resort hotel. As fate would have it, a stage show was in production at the resort and Simon was informed by one of the performers that the choreographer was looking for a gymnast. Simon somehow knew that this was going to be the first step towards a career on stage. Simon subsequently performed all over the world in various stage productions as a dancer/acrobat, culminating in his dream role as a performer at the world famous Moulin Rouge, Paris, in 1989.On his return to South Africa, Simon pursued his stage career as an actor. Whilst studying drama, Simon secured himself a modelling agent and enjoyed success in ramp, print and television commercials. Simon received recognition as a model in South Africa and was asked to enter the Mr. South Africa talent and action man competition. On winning this competition in 1992, Simon was offered an audition on a successful television series, Egoli: Place of Gold. After guest starring on the show for three months, he accepted a permanent contract for a lead role in the show, which he continued for six years.In 1997, he married his girlfriend in a game lodge in South Africa. After being personally affected by the high levels of crime in Johannesburg, he decided to immigrate to the USA, hoping for a better quality of life. This also gave him the opportunity to further his acting career.Arriving in 2000 in Los Angeles, Simon secured an agent, and landed a guest star role with Don Johnson on the hit TV series, Nash Bridges. A short time after that, he acquired the guest star role of Ba'al on Stargate SG-1. Cliff's combination of charming bad guy charisma and wicked sense of humor made him a viewer favorite antagonist, keeping his character recurring for five seasons. In 2008, Simon was brought back to play Ba'al in the Stargate movie Stargate: Continuum.