Callisto is an enormous bear that resides south of the Demonic Ruins, and is the only monster to drop the tyrannical ring. He attacks using melee. He can knock players back a few tiles, which renders them unable to move for a few seconds, as well as heal himself slightly. He is also able to perform a deadly shockwave attack that can hit up to 60.
Item Quantity Rarity GE market price Big bones 1 Always 199
Item Quantity Rarity GE market price Rune pickaxe 1 Common 18,843 Rune 2h sword 1 Uncommon 37,945 Dragon pickaxe 1 Rare (1/171) 5,930,709 Dragon 2h sword 1 Rare (1/256) 133,084 Tyrannical ring 1 Rare (1/512) 1,441,763
Item Quantity Rarity GE market price Soul rune 250 Uncommon 36,750 Death rune 300 Uncommon 66,600 Chaos rune 400 Uncommon 40,000 Blood rune 200 Uncommon 53,600
Item Quantity Rarity GE market price Uncut ruby 20 (noted) Uncommon  29,180 Uncut diamond 10 (noted) Uncommon  27,850 Coconut 60 (noted) Uncommon 78,180 Crushed nest 75 (noted) Uncommon 225,600 Magic logs 100 (noted) Uncommon 115,100 Limpwurt root 25 (noted) Uncommon 22,450 Red dragonhide 75 (noted) Uncommon 186,750 Mahogany logs 400 (noted) Uncommon 170,000 Uncut dragonstone 1 Rare (1/128) 13,857 Grimy toadflax 100 (noted) Rare (1/128) 114,400
Item Quantity Rarity GE market price Snapdragon seed 3 Uncommon 143,757 Ranarr seed 5 Uncommon 187,295 Yew seed 1 Rare (1/128) 96,856 Magic seed 1 Rare (1/128) 155,521 Palm tree seed 1 Rare (1/128) 36,782
Item Quantity Rarity GE market price Dark crab 8 Common  11,344 Super restore(4) 3 Common  30,606
Item Quantity Rarity GE market price Coins 12,000–20,000 Common Not sold Supercompost 100 (noted) Uncommon 52,100 Cannonball 250 Uncommon 43,750 Mysterious emblem 1 Uncommon (1/27.5) 162,934 Looting bag 1 Uncommon (1/30) Not sold Slayer's enchantment 1 Uncommon (1/30) 1,080 Clue scroll (elite) 1 Rare (1/100) Not sold Dark fishing bait 375 Rare (1/128) 750 Long bone 1 Rare (1/400) Not sold Callisto cub 1 Very rare (1/2,000) Not sold Curved bone 1 Very rare (1/5,000) Not sold
- ↑ Only dropped while on a slayer assignment given by Krystilia, unless the kill was done on the official Bounty Hunter world. Killing Callisto on the Bounty Hunter also increases the drop rate from 1/27.5 to 1/5.
- ↑ Only dropped while on a slayer assignment given by Krystilia.
- ↑ 1/50 if a Ring of wealth (i) is worn.
- Callisto is named after one of the Greek god Zeus' many lovers, who was turned into the constellation Ursa Major.
- Upon release, Callisto had a slightly worse drop table. In addition, players could exploit his low Magic by safespotting him with the trident of the seas behind a cluster of skeletons north of him. The cluster of skeletons have been removed and Callisto is now immune to Magic damage.
- Callisto is the name of one of Jupiter's moons.
- His examine text is a reference to Goldilocks and the Three Bears.
- There is a pile of bear droppings in the woods south of his spawn, with the examine text "Now you know." — a reference to the popular colloquialism, "Does a bear shit in the woods?", a rhetorical question in response to something where the answer is obviously yes.