社会主义阵线
Dr. M. K. Rajakumar (25 May 1932 – 22 November 2008) was a Malaysian doctor and socialist politician. As a doctor, he was a pioneer of the discipline of Family Medicine by general practitioners in Malaysia. As a leftist intellectual he was among the leaders of the Labour Party of Malaya and Barisan Sosialis in the 1960s, helping to build the Labour Party alongside Tan Chee Khoon, V. David, Ishak Haji Muhammad (better known as Pak Sako) and Karam Singh.