Nellie Constance Martyn (12 June 1887 – 28 November 1926) was an Australian businesswoman who became managing director of Steel Company of Australia on her father's death.

[1] A former president of the Victorian Chamber of Manufactures, he represented Australian employers at the International Labour Conference in Geneva in October 1923.

[5] While in London he died of pneumonia and Martyn became managing director of the family business, Steel Company of Australia.

Mourners included Sir William McPherson, later Premier of Victoria, and Essington Lewis, managing director of BHP Steel, as well as committee members of the Young Women's Christian Association.

The Argus reported that the "funeral cortege was a mile and a quarter in length, while hundreds of wreaths from business firms in Melbourne were received.

quoted Sir John Monash, who had led a tour of Yallourn by Melbourne business people some years earlier: "The best man of the whole lot was Miss Martyn".