This drop guid was made with info from playing many private servers:
The monster listed are only monsters that drop stuff:
Dagganoth:
d hally
addy scimmy
R2H
clue scroll
capes
bones
Prime:
rune c'bow
dragon wc axe
seers ring
berserker ring
clue scroll
Rex:
rune c'bow
dragon wc axe
warriors ring
berserker ring
clue scroll
Supreme:
rune c'bow
dragon wc axe
archers ring
berserker ring
clue scroll
Hill Giant/Moss Giant:
R2H
rune platebody
rune platelegs
rune plateskirt
rune full helm
dragon sq sheild
dragon med helm
dragon scimmy
capes
str ammy
big bones
Elf Warriors:
crystal bow
crystal sheild
addy platebody
addy platelegs
addy plateskirt
addy med helm
addy full helm
bones
King Black Dragon:
rune platebody
rune platelegs
robin hood
ranger boots
bandos chestplate
bandos tassys
zamorak godsword
dragon skimmy
Anti-dragon sheild
clue scroll
Dragon bones
Mith Dragon:
super atk/str/def pots
Dragon full helm
Dragon Fire Sheild
Clue scroll
Dragon bones
Green Dragon:
anti-dragon sheild
acient staff
oynx neckless
oynx ring(really rare)
dragon platelegs
dragon plateskirt
dragon battle axe
clue scroll
dragon bones
Khazard mini-game monsters:
Khazard armour
Khazard helm
bones
Kaliphite Queen:
Dragon chainbody
Dragon 2Hander
Dragon boots
Clue scroll
Jelly:
book of balance
holy book
unholy book
Mithril full helm
Turoth:
rune kite sheild
Dust devil:
12k coins
dragon boots
dragon chain
dragon med helm
clue scroll
ashes
Nechryael:
rune boots
dragon boots
clue scroll
Abyssal Demond:
abyssal whip
clue scroll
Dark Beast:
dark bow
clue scroll