Bertha McNamara
 Bertha McNamara Bredt (née Matilda Emilie Bertha Kalkstein 28 September 1853 – 1 August 1931) was a Sydney-based Australian socialist agitator feminist pamphleteer bookseller and mother-in-law of Australian writer Henry Lawson. Born in Germany she migrated to Victoria via England in 1869. After the death of her husband Peter Hermann Bredt she became a political activist and published Home Talk on Socialism (1891) one of Australia's first pamphlets on socialism.