Ignatius Johannes Rens (19 July 1929 – 19 December 1989) was a South African dual–code international rugby player.
Born in Potchefstroom, Rens started out in rugby union. He was a Transvaal representative player, capped twice for the Springboks, both times as a fly–half in their home series against the Wallabies in 1953. Coming into the XV for the third Test match in Durban, Rens contributed three conversions in a 18-8 win, then for the final Test match in Port Elizabeth kicked a further 13 points in another Springboks win, which included a drop goal.
Rens later switched to rugby league and played as a five–eighth for Southern Suburbs. In 1963, Rens was a member of the first South Africa national rugby league team to undertake a tour of Australia.
Originally a farmer, Rens also operated the "Punch Bowl" hotel in Transvaal for a period in the 1970s.