Martyrs who held to the doctrines of grace.
Paul having received the doctine from God and after writing them and sharing with others was put to death.
Many who were killed doing the 3 major Roman persecutions cannot be claimed as only free-willers.
Augustine of Hippo resist the Vandals Arian heresy and was killed because of it.
The Waldenses, are well known for their hold to the doctrines of grace and had numerous martyrdoms. The Waldenses met with Luther, and asked Calvin to translate the Bible into French. If I remember right, it was Calvin's cousin that Calvin asked to translate this for them.
Wycliffe did not die because of his faith, but the RCC sure wanted it that way. Three decades after his death, Wycliffe's bones were dragged from their grave and burned.
John Huss, the proselyte of Wycliffe, and a believer of the tenents of grace, was burned to death.
Jerome of Prague, was likewise burned.
William Sautre, John Claydon, Thomas Bilvey, Tyndale, James Bainham, John Lambert, and Robert Barnes were all burned to death for the Christian faith.
Cranmer, Ridley, Latimer , and John Hooper (1495-1554), also died in flames of fire.
John Foxe, not a martyr, but martyr-historian ["Foxe's Book of Martyrs"], was also a Calvinist.
Now this list about is not full. This is mainly leaders.
Augustus Toplady once challenged the Arminians of his time to produce evidence that an Arminian had ever gone to death in martyrdom.
I can think of one. Is there another?