I have no idea whether I have ever met a Bodhisattva. In Theravadin Buddhism this is a very limited group of people around 26. I say 26 because when our Buddha 500 lifetimes ago vowed to become a Buddha, he became a Bodhisattva at that time and I believe there were 25 or 26 other Buddhas in between that time period of when he vowed and he became a Buddha. So basically "he got in line", he was about number 26.
In the Mahayana Tradition, including Tibetan Buddhism, Chinese, Zen and so on, they believe everyone can become a Bodhisattva. That is very different to Theravadin Buddhism, where there are only about 26. Also according to what I have read, most of Bodhisattvas don't exist as humans. They are in the heaven realms. They come in human form from time to time, but it is impossible to know who they are, sorry, there is no halo, it is impossible to know. It is possible that I am a Bodhisattva but I don't know.
In the Jataka stories, which are the stories about the Buddha in his 500 lives in-between vowing and becoming a Buddha, in some of them supposedly he did know he was a Bodhisattva, and he worked on the Paramis development. There are other times when he did not know. This is another consideration to keep in mind, that you may not even know that you are one yourself.
Are there other Bodhisattvas in other religions? Not that I know of. It is a term that is just within Buddhism and I don't think anyone else has them. It doesn't stop a person though from being very good, very kind, very wise. If we take a look at someone I mentioned yesterday, Mother Teresa, she was certainly someone who can be admired for developing her Paramis to a high level. That can be an inspiration.