Lewis Norman Mander, , FAA, FRS (8 September 1939 – 8 February 2020) was a New Zealand-born Australian organic chemist. He has widely explored the synthesis and chemistry of the gibberellin class of diterpenes over a 20-year period at the Australian National University (ANU). In particular, he studied the effect of these hormones on stem growth and on the reasons why plant undergo bolting during plant development. The July 2004 edition of the Australian Journal of Chemistry was dedicated to Mander on the occasion of his 65th birthday. He retired in 2002 but remained active at the ANU until 2014. In 2018 Mander was made a Companion in the General Division in the Order of Australia which "...is awarded for eminent achievement and merit of the highest degree in service to Australia or humanity at large".
In an interview he gave after winning his award, Mander said that his goal was to improve the efficiency of extracting food from plants with the possibility of reducing food shortages in the future.