Does anyone know the title and authors of these books?

When I was younger I read these two series of books, and I can't remember the titles or the authors.
1. A short series of a girl who lived on a planet alone, with a robot that cared for her, and she had green skin. It's set in the future, when colonies of humans go to settle on other planets. She was made to have green skin so she could handle the high UV radiation….
2. About a man who went to this other world, became the king (I think), and married a woman who had green (I think) skin? She was from the forest.
This is all I can remember :( Can someone please help me?