Slayer tasks can be retrieved from Kuradel. You can walk to her as she is east (->) of bank or type ::slayer. She offers three types of tasks (Regular/Boss/Wilderness) and four difficulties (Short/Medium/Long/Extreme). Difficult is basically length. Short can be 3-15 kills while extreme can be up to 100+
Players can use the portal next to Kuradal's house to Teleport to task for 5,000 GP. See the slayer list below for potential tasks
PSA: You can still get lower level tasks at higher slayer level, e.g. getting Fire giants (Req 21 Slayer) at level 96. However, you cannot get a task that has higher level than yours.
Regular Tasks
Level 1: Chicken, Crawling hand, Rock crab, Hill giant, Ghost, Minotaur, Cave crawler, Black knight, Bats, Skeleton, Chaos druid & Monk of zamorak Level 5: Jungle spiders Level 10: Ice giant, Ice warrior & Ankous Level 11: Moss giant Level 12: Dagannoth Level 13: Hobgoblin Level 15: Banshee Level 21: Fire giant Level 23: Lesser Demon Level 24: Cocaktrice Level 26: Baby blue dragon Level 32: Pyrefiend Level 33: Greater demon Level 40: Basilisk Level 45: Infernal mage Level 50: Bloodveld Level 51: Blue dragon Level 52: Jelly Level 53: Black dragon Level 55: Turoth Level 56: Hellhound Level 57: Steel & Iron Dragons Level 58: Cave horror Level 59: Mithril dragon Level 60: Black demon Level 65: Dust devil Level 70: Kurask Level 73: Jungle Strykewyrm Level 75: Gargoyle Level 77: Desert Strykewyrm Level 78: Aquanite Level 85: Abyssal demon Level 87: Waterfiend Level 90: Dark Beast Level 91: Edimmu Level 93: Ice Strykewyrm
Boss Tasks
Level 50: KBD, Skeletal Horror, Bork & DKS Level 75: Corporeal Beast Level 88: Abyssal Spider Level 95: Rammernaut Level 98: Nomad Level 99: Lucien & Forgotten Beholder
Wilderness Tasks
Level 1: Dark warrior, Zombie, Grizzly bear, Thugs, Wilderness chaos druid, Earth warrior, Skeleton, Ghosts, Scorpons & Bandits Level 3: Pirate Level 5: Poison spiders Level 7: Red spiders Level 10: Ankou Level 13: Green dragon Level 15: Rev hobgoblin Level 17: Magic axes Level 20: Rev vampire Level 25: Rev werewolf Level 26: Greater demon Level 30: Rev hellhound Level 35: Rev giant Level 40: Rev demon Level 42: Elder chaos druids Level 44: Black demon Level 45: Rev ork Level 50: Rev dark beast Level 51: Hellhound Level 52: Battle mages Level 55: Brutes Level 58: Tormented demons (💀 Boss) Level 60: Rev knight Level 63: Necromancer (💀 Boss) Level 65: Rev dragon Level 70: Wildywyrmy Level 75: Rogue Level 80: Icefiend Level 85: Abyssal demon