Robert Odjahan Tambunan, known as RO Tambunan, was born on July 24, 1935, in North Tapanuli, North Sumatra and died on September 5, 2015, in Bekasi, West Java.

He was an Indonesian lawyer veteran and politician from the Indonesian Democratic Party of Struggle.

Robert became popular when he became the lawyer of the Chairman of the Indonesian Democratic Party (PDI) and for Megawati Sukarnoputri on the case of the invasion of the PDI office on July 27, 1996.

He led the Indonesian Democracy Defenders team (the defense team) from 1997 to 1999 that advocated the case.

RO Tambunan passed away at 80 yrs old.