Phobias - Beginning with O

Obesophobia- Fear of gaining weight.(Pocrescophobia)
Ochlophobia- Fear of crowds or mobs.
Ochophobia- Fear of vehicles.
Octophobia - Fear of the figure 8.
Odontophobia- Fear of teeth or dental surgery.
Odynophobia or Odynephobia- Fear of pain. (Algophobia)
Oenophobia- Fear of wines.
Oikophobia- Fear of home surroundings, house.(Domatophobia, Eicophobia)
Olfactophobia- Fear of smells.
Ombrophobia- Fear of rain or of being rained on.
Ommetaphobia or Ommatophobia- Fear of eyes.
Omphalophobia- Fear of belly buttons.
Oneirophobia- Fear of dreams.
Oneirogmophobia- Fear of wet dreams.
Onomatophobia- Fear of hearing a certain word or of names.
Ophidiophobia- Fear of snakes. (Snakephobia)
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 or Osphresiophobia- Fear of smells or odors.
Ostraconophobia- Fear of shellfish.
Ouranophobia or Uranophobia- Fear of heaven.