Cathal

Could be used as a male form of Catherine. Also good that it sounds like Catholic, as it's Irish.

Seeing that my name is Cathal I feel I have the right to comment on it. For children the name is impossible to pronounce leading to comical abbreviations such as Cockles. Also as it is an Irish name people from other countries often have trouble with it, leading usualy to you having to spell it for them. But it is for this reason, the Irishness of the name, that I love it.