县令，尊称县太爷、县大老爷。是中国古代县级行政区划的最高官员名称，掌握所管辖区域的行政、司法、审判、税务、兵役等大权。县令下设县丞、主簿、县尉、典史等。

战国时秦国商鞅变法，将许多小乡合并为县，并县后的行政长官便称为「令」。

最初，县令直接由国君任免，但在战国末年，地方行政制度形成郡县两级制，县隷属于郡，县令就成了郡守的下属。秦汉时，法令规定根据县的人口多寡，县官的职称也不同，一万户以上称县令，以下称县长。

秦汉时，县令品秩八百石至千石，考绩优良者可辟为府椽、甚至可以升为郡守。所以县令颇为人所重，朝廷也深重其选。魏晋南北朝时期，县令多以年老胥吏或退役的下级军官充任，品秩既低，所任之人又及其颟顸、贪暴，为士人所不齿，地方亦多不治。而到宋代 ，遣京朝官分知县事，简称知县。元朝时改为县尹；到明清时恢复。

County magistrate (Chinese:县令; pinyin:xian ling or simplified Chinese:县长; traditional Chinese:縣長; pinyin:xiànzhǎng sometimes called local magistrate, in imperial China was the official in charge of the xian, or county, the lowest level of central government. The magistrate was the official who had face-to-face relations with the people and administered all aspects of government on behalf of the emperor. Because he was expected to rule in a disciplined but caring way and because the people were expected to obey, the county magistrate was informally known as the Fumu Guan (Chinese:父母官; pinyin:fùmǔ guān), the "Father and Mother" or "parental" official.