Formal:
* Cantankerous: Bad-tempered, argumentative, and uncooperative.
* Surly: Bad-tempered and unfriendly.
* Sullen: Gloomy and bad-tempered.
* Crabby: Grumpy and irritable, often associated with old age.
* Cross: Irritable and easily annoyed.
* Peevish: Easily irritated and complaining.
Informal:
* Cranky: Irritable and bad-tempered, often associated with old age.
* Grouchy: Bad-tempered and complaining.
* Mopey: Sad and gloomy.
* Grumbling: Complaining in a low voice.
* Sourpuss: A person who is always grumpy and unhappy.
* Curmudgeon: A bad-tempered and grumpy old man.
More specific:
* Misanthropic: Disliking or distrusting other people.
* Dyspeptic: Suffering from indigestion, and therefore irritable.
* Irascible: Easily angered.
* Testy: Easily irritated and impatient.
* Cantankerous: Aggressive and bad-tempered.
The best word to use will depend on the specific context and the tone you want to convey.