My favourite authors for the genres:
Horror: Sebastian Rook (Vampire Plagues), Meg Cabot (Mediator), Darren Shan (Demonata, Cirque du Freak), Christopher Pike (The Last Vampire), Brian Keene (Darkness on the Edge of Town), Seth Grahame-Smith (Abraham Lincoln, Vampire Hunter; Jane Slayre; Pride and Prejudice and Zombies), Rick Yancey (Monstrumologist, the Fifth Wave), Rhiannon Lassiter (Hex), Marcus Sedgwick
Mystery/Thriller: Dan Brown (Digital Fortress, Deception Point, Robert Langdon), Anthony Horowitz (Alex Rider), David Moody (Hater), Lemony Snicket (A Series of Unfortunate Events), Dia Reeves (Bleeding Violet), Sidney Sheldon
Fantasy: J K Rowling (Harry Potter), Jenny Nimmo (Charlie Bone), Meg Cabot (Avalon High, 1800-Where-R-U), Rick Riordan (Percy Jackson, Kane, Magnus Chase, Apollo, Demigods and Magicians), Katherine Roberts (The Seven Fabulous Wonders, Echorium), CS Lewis (Narnia), Alison Croggon (Pellinor), Alison Goodman (Eon), Diana Wynne Jones (Howl's Moving Castle), Michael Scott (Nicholas Flamel), Michelle Paver (Chronicles of Ancient Darkness), Terry Pratchett (Discworld), Christopher Paolini (Inheritance), David Eddings (Belgariad), Catherine Fisher (Chronoptika, Oracle, Incarceron), John Bellairs (Lewis Barnavelt)
YA Romance: Meg Cabot (Teen Idol), Sara Shepard (The Lying Game), Becca Fitzpatrick (Hush, Hush), Lauren Kate (Fallen), Thomas E Sniegoski (Fallen), Cassandra Clare (Mortal Instruments, Infernal Devices), Isaac Marion (Warm Bodies), LA Weatherly (Angel), Rebecca Lim (Mercy), Kami Garcia (Beautiful Creatures), Melissa de la Cruz (Blue Blood), Suzanne Collins (Hunger Games), Carrie Ryan (The Forest of Hands and Teeth), James Dashner (Maze Runner), Courtney Allison Moulton (Angelfire), Amy Plum (Die For Me), Yvonne Woon (Dead Beautiful), Kiersten White (Paranormalcy), Kody Keplinger (The DUFF), Philip Reeve (Mortal Engines), Kevin Kwan (Crazy Rich Asians), Alexandra Bracken (Darkest Minds), Jodi Picoult, Alice Sebold (The Lovely Bones)
Children: Jeff Kinney (Diary of a Wimpy Kid), Meg Cabot (Allie Finkle's Rules for Girls), Jacqueline Wilson (Tracy Beaker, Girls), Cressida Cowell (How to Train Your Dragon), Georgia Byng (Molly Moon),
Classic: Charlotte Bronte (Jane Eyre), Jane Austen (Pride and Prejudice), George Orwell (1984), Harper Lee (To Kill a Mockingbird), Charles Dickens, Arthur Conan Doyle (Sherlock Holmes),