威廉氏症候群（英语：Williams–Beuren syndrome, WBS）是一种罕见的神经发育异常，患者鼻根较低，拥有像小精灵的外观，且脸部特征随年龄增长而更加明显。大部分病人智能不足但语言能力较正常人好，行为举止异常兴奋且不怕生。症状还包括心血管疾病如主动脉瓣上狭窄与高血钙，此病在描述尚不完全时曾被部分医师称为自发性婴儿高血钙（idiopathic infantile hypercalcemia）。

威廉氏症候群最早于1961年由新西兰心脏学家J.C.P. Williams发现，其病因为7号染色体长臂约26个基因的缺失，发生率介于1/7500与1/20000之间。

Williams syndrome (WS), also known as Williams–Beuren syndrome (WBS), is a rare neurodevelopmental disorder characterized by: a distinctive, "elfin" facial appearance, along with a low nasal bridge; an unusually cheerful demeanor and ease with strangers; developmental delay coupled with strong language skills; profound visuo-spatial impairments; and cardiovascular problems, such as supravalvular aortic stenosis and transient high blood calcium.