Mary Martin died on November 3, 1990 at the age of 76.
she died of stomach cancer, but she thought she was pregnant. Read more: http://wiki.answers.com/Q/How_did_Mary_Tudor_die#ixzz1Zq1dZPdq
I noticed this in the question pool and it was submitted quite a while ago but I understand now why it has not been answered. This question needs clarification of which "Martin" you need to know...
he was shot at the back of his house
Her kingdom was attacked and an arrow hit her heart during the attack. The arrow still has her blood on it.