人格障碍，或人格（性格）疾患／异常／违常（Personality disorders）。是精神疾病中，对于一群特定拥有长期而僵化思想及行为病患的分类。这类疾患常可因其人格和行为的问题而导致社会功能的障碍。

人格违常是据美国精神医学学会所定，这类疾患的表现是跨文化和国界的。它们被定义成发病期至少要能追溯到成长期早期或更早。要能符合人格违常诊断的最低标准是疾患本身必须已干扰到个人、社会、或职业功能。

Personality disorders are a class of mental disorders characterized by enduring maladaptive patterns of behavior, cognition, and inner experience, exhibited across many contexts and deviating markedly from those accepted by the individual's culture. These patterns develop early, are inflexible, and are associated with significant distress or disability. The definitions may vary somewhat, according to source.