Book recommendations required

The colleague who lent me an awful Heinlein book last year apparently has some sort of contact with the person responsible for Asda's¹ book-buying policy, and he's asked her for some suggestions of fantasy and SF books he should be getting, both the classics and the new and shiny. She's got this idea that I read a lot of said genres, and asked me for additions to her list. Since her list is composed of people like Heinlein and Anne McCaffrey, she really needs² some pointers to the actually-good stuff out there, which is where you guys come in.

So, tell me your top five classic fantasy/SF authors, and your top five new and shiny fantasy/SF authors. I'll pass the list on, and maybe you'll be able to buy some of your choices in Asda in the future!

¹A British supermarket
²My estimation of her needs, not hers ;-)