Ochlophobia - Fear of crowds or mobs.

Ochophobia - Fear of vehicle.

Octophobia - Fear of the figure 8.

Odontophobia - Fear of teeth or dental surgery.

Odynephobia - Fear of pain.

Odynophobia - Fear of pain.

Oenophobia - Fear of wines.

Oikophobia - Fear of home surroundings, house.

Olfactophobia - Fear of smells.

Ombrophobia - Fear of rain or of being rained on.

Ommatophobia - Fear of eyes.

Ommetaphobia - Fear of eyes.

Oneirogmophobia - Fear of wet dreams.

Oneirophobia - Fear of dreams.

Onomatophobia - Fear of hearing a certain word or of names.

Ophidiophobia - Fear of snakes.

Ophthalmophobia - Fear of being stared at.

Opiophobia - Fear medical doctors experience of prescribing needed pain medications for patients.

Optophobia - Fear of opening one's eyes.

Ornithophobia - Fear of birds.

Orthophobia - Fear of property.

Osmophobia - Fear of smells or odors.

Osphresiophobia - Fear of smells or odors.

Ostraconophobia - Fear of shellfish.

Ouranophobia - Fear of heaven.