The God of the Old Testament is arguably the most unpleasant character in all fiction:
Jealous and proud of it;
A petty, unjust, unforgiving control-freak;
A vindictive, bloodthirsty ethnic cleanser;
A misogynistic, h*mophobic, racist,
Infanticidal, genocidal, filicidal, pestilential,
Megalomaniacal, sadomasochistic,
Capriciously malevolent bully