Felix Grundy (September 11, 1777–December 19, 1840) was a U.S. Congressman and U.S. Senator from Tennessee who also served as the 13th Attorney General of the United States.

Born in Berkeley County, Virginia (now Berkeley County, West Virginia), he moved to Brownsville, Pennsylvania and then Kentucky with his parents. He was educated at home and at the Bardstown Academy in Kentucky. He then studied law and was admitted to the Kentucky bar and commenced practice in Bardstown in 1797.

He was a member of the Kentucky constitutional convention in 1799, served in the Kentucky House of Representatives from 1800 to 1805 and was appointed associate justiceship in the State Supreme Court of Errors and Appeals, was Chief Justice in 1807, resigned the same year and moved to Nashville, Tennessee, where he again took up the practice of law.

He was elected as a Republican to the 12th and 13th Congresses and served from March 4, 1811, until his resignation in 1814.

He then became a member of the Tennessee House of Representatives from 1819 to 1825, and in 1820 was commissioner to settle the boundary line (state line ) between Tennessee and Kentucky. He was elected as a Jacksonian in 1829 to the United States Senate to fill the vacancy in the term ending March 4, 1833, caused by the resignation of John H. Eaton to join the Cabinet of President Andrew Jackson; reelected in 1832 and served from October 19, 1829, to July 4, 1838, when he resigned to accept a Cabinet position. During this time he served as chairman of the U.S. Senate Committee on Post Offices and Post Roads (21st through 24th Congresses), U.S. Senate Committee on the Judiciary (24th and 25th Congresses).

He entered the Cabinet when he was appointed Attorney General of the United States by President Martin Van Buren in July 1838. He resigned the post in December 1839, having been elected as a Democrat to the United States Senate on November 19, 1839, to fill the vacancy in the term commencing March 4, 1839, caused by the resignation of Ephraim Foster ; the question of his eligibility to election as Senator while holding the office of Attorney General of the United States having been raised, he resigned from the Senate on December 14, 1839, and was reelected the same day, serving from December 14, 1839, until his death in Nashville, almost a year to the day later. During this stint in the upper house of the U.S. Congress he served as chairman of the U.S. Senate Committee on Revolutionary Claims in the 26th Congress.

He is interred in Mount Olivet Cemetery in Nashville, Tennessee. There are four Grundy Counties, including the one in Tennessee, named in his honor.