The son of the famous Voortrekker leader Andries Pretorius, Marthinus Wessel Pretorius (17 September 1819 - 19 May 1901) was the first president of the South African Republic, and also compiled the constitution of the Republic.

After the death of his father in 1853, he was appointed as the Commandant - General of the ZAR (South African Republic) and moved from his farm Kalkheuwel, near Broederstroom, to the city of Potchefstroom. He was the last Head of State of Potchefstroom between 1853 and 1856.

In an endeavor to establish a new town, he bought two farms named Elandspoort en Daspoort between 1854 and 1855, on which he founded the city of Pretoria in 1855. He originally named the town Pretoria Philadelphia, in honour of his father and his father's brothers, but the name of the town was later shortened to just Pretoria. Five years later the capitol of the ZAR (South African Republic) was moved from Potchefstroom to Pretoria.

He served as the first president of Transvaal from 1857 to 1860. However in 1859, in an effort to create closer bonds of relationship with the Orange Free State, he simultaneously held the office of State President of the Orange Free State and that of president of the ZAR (South African Republic). This however created tension in Transvaal and he resigned the presidency of the South African Republic in 1860.

After serving in the presidency of the Orange Free State until 1863, he was reelected as president of the ZAR (South African Republic) in 1864 and served a second term until 1871.

Finally, he served a third term as joint head of state (triumvirate) of Transvaal between 1880 and 1883. He died in 1901 at Potchefstroom.