There are many who wish to see new mobs, and those who do not... but for those of us who do, why not have a repository for mob ideas? Feel free to critique mobs suggested and add your own!
I'll start off with a couple.
1) Goblins, small mobs about the size of baby villagers with brownish, green dotted skin and glowing green eyes (similar to the spiders but this one only has 2 LOL). It makes short and high pitched grunts and cackles as ambient noise. It throws small spears at a faster fire rate then skeletons but they do less damage. This mob has relatively low health (accounting for it's small stature) and upon death can drop sticks and flint. This mob only spawns in caves (as to make them not a completely common mob and similar too but not as rare as slimes), abandoned mineshafts and strongholds and maybe the Nether also? What makes this mob unique is that if zombies (also maybe zombie pigmen?) are around it can piggy back on them while still throwing the spear, it can be killed individually from the zombie like the spider jockey. This will make this mob a sort of clever but primitive native cave dweller that has learned to make a symbiotic relationship with at least one of the other native hostiles, which you can encounter while cave diving, they might occasionally wander to the overworld (and won't burn in sunlight if they do) but they should mainly only be encountered when cave diving (or in the Nether?).
2) Leapers, a pack insect resembling a praying mantis (but with only the front legs and the claws, it stands upright, about the size of a silverfish if it were standing up right head to tail), bright green skinned and makes short clicks and clacks as sounds. It spawns in and tries to attack in packs. What makes this mob unique is it's pack mentality and how it attacks. It moves slowly and methodically and always moves around in a pack, but when it spies a target, the rest of the leapers near it become hostile to that target as well. If they move slowly how can they be a threat you ask? Well it's how they attack, when they aquire a target they begin making leap strikes at it, they will go still for an instant and then leap forward a great distance making passes at it's target (similar to headcrabs in Half-Life). Individually they have low health and deal low damage, but remember they spawn in and act as a pack... they can drop some kind of bug slime that if you combine enough of it (i'm talking kind of alot of them) you get 1 slime ball. These can spawn anywhere it's dark, to give the world more of an insect presence, and perhaps spiders and leapers can on rare occasions become hostile to one another, because an insects gotta eat...
Basically I feel that minecraft could use a couple more native mobs that have interactions with other mobs and make the world feel more alive and populated, and that are frailish to make a sort of lower tier in the worlds food chain but make up for that in some way (piggy backing or working as a pack), and that provide simple drops that are of some small worth and not dropped by anything else currently (sticks and flint) or might otherwise be very very difficult or too rare to obtain (slimeballs).
I'll start off with a couple.
1) Goblins, small mobs about the size of baby villagers with brownish, green dotted skin and glowing green eyes (similar to the spiders but this one only has 2 LOL). It makes short and high pitched grunts and cackles as ambient noise. It throws small spears at a faster fire rate then skeletons but they do less damage. This mob has relatively low health (accounting for it's small stature) and upon death can drop sticks and flint. This mob only spawns in caves (as to make them not a completely common mob and similar too but not as rare as slimes), abandoned mineshafts and strongholds and maybe the Nether also? What makes this mob unique is that if zombies (also maybe zombie pigmen?) are around it can piggy back on them while still throwing the spear, it can be killed individually from the zombie like the spider jockey. This will make this mob a sort of clever but primitive native cave dweller that has learned to make a symbiotic relationship with at least one of the other native hostiles, which you can encounter while cave diving, they might occasionally wander to the overworld (and won't burn in sunlight if they do) but they should mainly only be encountered when cave diving (or in the Nether?).
2) Leapers, a pack insect resembling a praying mantis (but with only the front legs and the claws, it stands upright, about the size of a silverfish if it were standing up right head to tail), bright green skinned and makes short clicks and clacks as sounds. It spawns in and tries to attack in packs. What makes this mob unique is it's pack mentality and how it attacks. It moves slowly and methodically and always moves around in a pack, but when it spies a target, the rest of the leapers near it become hostile to that target as well. If they move slowly how can they be a threat you ask? Well it's how they attack, when they aquire a target they begin making leap strikes at it, they will go still for an instant and then leap forward a great distance making passes at it's target (similar to headcrabs in Half-Life). Individually they have low health and deal low damage, but remember they spawn in and act as a pack... they can drop some kind of bug slime that if you combine enough of it (i'm talking kind of alot of them) you get 1 slime ball. These can spawn anywhere it's dark, to give the world more of an insect presence, and perhaps spiders and leapers can on rare occasions become hostile to one another, because an insects gotta eat...
Basically I feel that minecraft could use a couple more native mobs that have interactions with other mobs and make the world feel more alive and populated, and that are frailish to make a sort of lower tier in the worlds food chain but make up for that in some way (piggy backing or working as a pack), and that provide simple drops that are of some small worth and not dropped by anything else currently (sticks and flint) or might otherwise be very very difficult or too rare to obtain (slimeballs).