My own list of agents is a bit muddled. Here are a few, but I know of others too, if anyone needs me to find more names.
Harry Illingworth, Robbie Guillory, Zoë Plant, Jamie Cowen, Sandra Sawicka, Shiel Land Associates, Meg Davis, Lucy Irvine, Ed Wilson, Anne C. Perry, Julie Crisp, John Jarrold, Max Edwards, John Baker, Hannah Bowm, Jennifer Goloboy, Stacia Decker, Jodi Reamer, Moe Ferrera, Naomi Davis, Jim McCarthy, Alexander Cochran, Robert Kirby, Rose Ferrao, Cameron McClure, Juliet Mushens, Maddy Belton, Laura Bennett.
I own the WRITER'S AND ARTIST'S YEARBOOK but honestly I've found it pretty unhelpful myself, as a writer of SFF. It's really not easy to navigate the book in order to find SFF agents. Much more fruitful to search the internet, or just try to stay "in the loop" with other writers and publishing people.
There ARE more agents out there. And there are some agents/agencies that seem to be perpetually closed to submissions, such as Zeno.