MartyrHistorically, a martyr (from Greek martys for "witness") was considered to be a person who died for their religious faith, typically by being tortured to death.
Christian martyrs in the first three centuries A.D. were crucified in the same manner as Roman political prisoners or eaten by lions as a circus spectacle. Many church historians claim that there were more Christian martyrs in the 20th century than in the first 19 centuries combined.
The term has since been used metaphorically for people killed in a historical struggle for some cause, such as Steve Biko or Rachel Corrie, or those whose deaths served to galvanize a particular movement, such as Matthew Shepard.
Hero or Villain?
The term "martyr" is in some ways a semantically interchangable with "hero" -- both are almost always controversial. The phrase 'one man's hero is another's criminal' is a simple way of expressing this disparity. Warriors throughout history return from battle are typically revered for "heroism" and "bravery" --regardless of the criminal acts they committed during war. In all cultures, war dead are considered to be in some sense "martyrs." This is true of the US soldier killed in the Iraq war--the US President commonly refers to "their sacrifice" as being "for the cause of freedom." This claim is of course but one point of view, and the veracity of such a claim tends to be measured not in the merits, but in terms of the outcomes of conflict. ("History is written by the victor.")
Suicide bombers (or homicide bombers) in Palestine are typically hailed as "martyrs" by many Palestinans (the actual percentage is also disputed). The cause of Palestinian freedom or nationalism tends to be hurt by the targeting of Israeli civilians by terrorists, and terrorism is generally denouced as a form around the world--not necessarily for its criminality, but for its use against strong civilized nations as a way to circumvent military might. The disctinction between martyr and criminal tend to follow the same politicized distinctions between "soldier" and "terrorist".