Martyr
A Martyr is someone who suffers persecution and later assassination or death for advocating or renouncing(to give up) or refusing to renounce(not giving up) or advocate, a religious belief or other cause as demanded by an external party.
Originally it was applied only to those who suffered for their religious beliefs but now the term has come to be used in connection with people killed for a political or nationalist cause as well.
Martyr Media
The Christian Martyrs of Japan; 17th-century Japanese painting
Sculpture at Mehdiana Sahib of the execution of Banda Singh Bahadur by Mughals in 1716
From the gallery of 20th century martyrs at Westminster Abbey—l. to r. Mother Elizabeth of Russia, Rev. Martin Luther King Jr., Archbishop Óscar Romero and Pastor Dietrich Bonhoeffer
The painting commemorating the martyrdom of the 3rd Shia Imam Husayn ibn Ali at the Battle of Karbala, 680 AD
Interior of the Coliseum at the National Shrine of the North American Martyrs, Auriesville, New York, showing the sanctuary and high altar.