Monsters.

Bosses
On Simplexus there is 13 bosses and these are:

General Graardor, Kree'arra, Commander Zilyana, K'ril Tsutsaroth (Access Pass only), King Black Dragon, Chaos Elemental, Dagannoth Kings (Supreme, Prime, and Rex), Corporeal Beast, Tormented Demons, Avatar of Destruction, and Barrelchest.

Slayer Monsters
Blue Dragons.

Level 111 Experience for Non-donator = 2,180, Donator = 3,270 Drops Dragon Bones Blue Dragonhide 100,000gp Rune Spear Dragon Platelegs.

Hellhounds Level 122 Experience for Non-Donator = 2,320, Donator = 3,480. Drops Bones

Abyssal Demons Level 124 Experience for Non-Donator = 3,000, Donator = 4,500 Drops Abyssal Whips. 2,500,000gp Ashes. Rune Javlin. Rune Kiteshield. Uncut Sapphire, Emerald, Ruby, Diamond. Chaos runes. Air runes. Rune Med Helm. Rune Chainbody. Rune Arrows. Rune Battleaxe. Dragonstone.

Hill Giant Level 28 Experience for Non-Donator = 700, Donator = 1,050 Drops Big Bones Rune Spear Rune Arrows Rune Full Helm 1,200gp Rune Plateskirt

Dagganoths Level 98 Experience for Non-Donator = 1,700, Donator = 2,550 Drops bones

Minigame Monsters
Ahrim the Blighted, Dharok the Wretched, Guthan the Infested, Karil the Tainted, Torag the Corrupt, Verac the Defiled. TzTok-Jad.