I can comment on the issue of rape in ancient Greece. My main source being Lysias 1 in which Lysias (a logographer) writes a defence speech for Euphiletos who has just killed a man named Eratosthenes after catching him sleeping with his wife. Lysias was considered on of the greatest "lawyers" Athens had ever seen. Given that, remember that it would not be likely that a great lawyer as Lysias would use anything outside of social norms to defend his client. By this I mean he would only use principles that would appeal to the jury (white, Athenian citizens). In this defence speech there is a portion where Lysias writes: [32] You hear, gentlemen, that it lays down that if anyone rapes a free man or child, he owes double the damages. If he rapes a woman, in those cases that carry the penalty of death, he is liable at the same rate. Thus, gentlemen, rapists are thought to deserve a lighter penalty than seducers, because the law condemned the latter to death, but assigned double the amount of the damages to the former.

This is in fact not true, as rapist have to pay double the fine of a seducer (someone who sleeps with your wife or concubine). But what is interesting here is that the social implications of what Lysias attempts to do. The idea of inheritance of land from father to son in ancient Greek culture is so engrained in society such that the paternity of a child is of outmost concern, i.e who the real father is or has the mother slept with another man. Lysias thinks that although the law gives rapists a harsher punishment, the social norms of society at the time believe that seducers (the people that ruin inheritance and debase society) are of more law breaking behaviour than rapist are. This idea is an interesting one as it pits social norms of the time against what the law actually says. We do not know if Lysias client was found guilty or not (although he did admit to the murder quite bluntly). You may also want to refer to Draco's homicide law which gives some exceptions as to when a man can kill another man. Note: I am not a historian, but I have taken numerous classical courses and am currently taking Ancient Crime and Punishment.

I can answer for Rome. There are two major sources for roman attitude toward rape the first is the rape of Lucretia by Livy. Now there is some debate as to the veracity of the story however it is still illuminating on the attitudes of Romans on that era. In that story. Rape is described as an unspeakable crime against both the woman and her husband. Since in that story the rape of a woman leads to the overthrowing of the last king of Rome. The other major source is the works of Quintellian which is one of the only surviving roman legal textbooks for lack of a better word. The rape of a man is the very worst crime according to him put up there with parricide and robbing a temple. The other thing to remember with rape in Rome is that it was one of the few crimes were the death penalty was applied. However it must be kept in mind that this only applies to highborn people raping slaves if you were not the owner was a form of property crime with the punishment a fine. If you were a prostitute there was no case where you could be raped. It was thought that you had given up your rights by prostituting yourself.

Not sure if this is ancient enough but in the 1400's, specifically England, one of rape's definitions was 'adultery with a woman of station without her husband's will or knowledge.'

The logic behind it was pretty simple. No married noblewoman could possibly commit adultery of her own free will. So if you had sex with a noblewoman in that fashion, you had to have taken her by force. Obviously this is sheer nonsense but it was a good way to save face for the people involved. The husband got to avoid being known as having been cuckolded, the woman avoids the stigma of adultery, and the only loser here is the one imprisoned.

A pretty famous case of this was Thomas Malory, the man who would be known for writing Le Morte d'Arthur, a compilation of various stories about King Arthur. He was imprisoned for 'raping' Joan Smith (or Smythe) not once but twice. It's a bit of conjecture, but some people like to think the reason he wrote a lot about Lancelot who is famous for his moment of weakness with Queen Guinevere was because he emphasized with the Knight.