| Cave bug [] | 65–85 | 1/52,428.8 |
| Cave crawler [] | 65–85 | 1/262,144 |
| Cave crawler [] | 65–85 | 1/87,381.33 |
| Cave horror [] | 65–85 | 1/3,200, 3 rolls |
| Cave slime [] | 65–85 | 1/65,536 |
| Celestial dragon (Dragonkin Laboratory) (Normal mode) [] | 65–85 | 1/2,400 |
| Champion of Infernus [] | 65–85 | 1/50,790.4 |
| Chaos druid [] | 65–85 | 1/262,144 |
| Chaos druid warrior [] | 65–85 | 1/262,144 |
| Chaos dwarf [] | 65–85 | 1/52,428.8 |
| Chaos dwarf (Chaos Dwarf Battlefield) [] | 65–85 | 1/52,428.8 |
| Chaos dwarf [] | 65–85 | 1/51,609.6 |
| Chaos dwarf hand cannoneer [] | 65–85 | 1/54,067.2 |
| Chaos dwogre [] | 65–85 | 1/60,620.8 |
| Chaos Elemental (Members) [] | 65–85 | 1/1,580.7, 2 rolls |
| Chaos Giant [] | 65–85 | 1/3,200 |
| Chaos witch apprentice (Normal mode) [] | 65–85 | 1/2,400 |
| Chaos witch channeler (Level 143 (Normal mode)) [] | 65–85 | 1/2,400 |
| Chaos witch lifeweaver (Normal mode) [] | 65–85 | 1/2,400 |
| Chaos witch magus (Normal mode) [] | 65–85 | 1/2,400 |
| Chaos witch mender (Normal mode) [] | 65–85 | 1/2,400 |
| Chaos witch (Normal mode) [] | 65–85 | 1/2,400 |
| Chest (Scabarite Cavern) [{'content': 'Estimated rarity may be inaccurate due to a low sample size.', 'name': 'inaccurate'}] | 1–3 | 42/750 |
| Cloaked zealot (Normal mode) [] | 65–85 | 1/2,400 |
| Cloaked zealot (Normal mode) [] | 65–85 | 1/2,400 |
| Cockatrice [] | 65–85 | 1/131,072 |
| Cockroach drone [] | 65–85 | 1/43,690.67 |
| Cockroach soldier [] | 65–85 | 1/37,449.14 |
| Cockroach worker [] | 65–85 | 1/52,428.8 |
 Coeden[{'content': 'Available after completing the elite Tirannwn achievements. Can only be claimed once per week.', 'name': 'eta'}] | 0–98 | Always |
| Commander Zilyana (Hard mode) [] | 30–40 | 8/128 |
| Commander Zilyana (Hard mode) [] | 65–85 | 1/1,600 |
| Commander Zilyana (Normal mode) [] | 65–85 | 1/1,580.7 |
| Cooper (Normal mode) [] | 65–85 | 1/2,400 |
| Corporeal Beast [] | 75 | 12/512 |
| Corporeal Beast [] | 65–85 | 1/104,857.6, 10 rolls |
| Corrupted dust devil [] | 65–85 | 1/2,400 |
| Corrupted kalphite guardian [] | 65–85 | 1/2,400 |
| Corrupted kalphite marauder [] | 65–85 | 1/2,400 |
| Corrupted lizard [] | 65–85 | 1/2,400 |
| Corrupted scarab [] | 65–85 | 1/2,400 |
| Corrupted scorpion [] | 65–85 | 1/2,400 |
| Corrupted worker [] | 65–85 | 1/2,400 |
| Crassian Leviathan (Normal mode) [] | 65–85 | 1/2,400 |
| Crassian scout (Normal mode) [] | 65–85 | 1/2,400 |
| Crassian scuttler (Normal mode) [] | 65–85 | 1/2,400 |
| Crassian warrior (Normal mode) [] | 65–85 | 1/2,400 |
| Crawling hand [] | 65–85 | 1/131,072 |