| Barnabas Kelet Hanagan | |
| Office: | Secretary of State of South Carolina |
| Term: | December 2, 1846 - December 7, 1850 |
| Governor: | David Johnson Whitemarsh B. Seabrook |
| Predecessor: | Robert Q. Pinckney |
| Successor: | Benjamin Perry |
| Order2: | 58th |
| Office2: | Governor of South Carolina |
| Term Start2: | April 7, 1840 |
| Term End2: | December 9, 1840 |
| Lieutenant2: | None |
| Predecessor2: | Patrick Noble |
| Successor2: | John Peter Richardson II |
| Order3: | 38th |
| Office3: | Lieutenant Governor of South Carolina |
| Term Start3: | December 7, 1838 |
| Term End3: | April 7, 1840 |
| Governor3: | Patrick Noble |
| Predecessor3: | William DuBose |
| Successor3: | William K. Clowney |
| Office1: | Member of the South Carolina Senate from Marion District |
| Term1: | November 25, 1844 - December 2, 1846 |
| Predecessor1: | Benjamin Gause |
| Successor1: | Robert Harllee |
| Office4: | Member of the South Carolina Senate from Marlboro District |
| Term4: | November 24, 1834 - November 26, 1838 |
| Predecessor4: | Robert Blair Campbell |
| Successor4: | Daniel C. Murdoch |
| Birth Date: | 7 June 1798 |
| Birth Place: | Marlboro District |
| Death Place: | Charleston, South Carolina |
| Resting Place: | Rogers Cemetery, Marlboro County, South Carolina |
| Alma Mater: | Heidelberg University |
| Profession: | physician, planter |
Barnabas Kelet Henagan (June 7, 1798January 10, 1855) was a physician and South Carolina politician who became the 58th Governor due to the death of Patrick Noble on April 7, 1840.
Henagan was born in Marlboro District on June 7, 1798, to Darby and Drusilla Henegan. He was educated at the academies in Marlboro County and he went on to study medicine at the University of Heidelberg in Germany. Afterwards he returned to South Carolina to practice medicine as a physician and he also engaged in planting. In 1826, he became the president of the Brownsville Minerva Academy.
Henagan won election to the South Carolina Senate in 1834 and was elected by the General Assembly to be the 38th Lieutenant Governor of South Carolina in 1838. In the final year of his term, Governor Patrick Noble died on April 7, 1840, and Henagan assumed the governorship. His term as governor lasted less than a year, but Henagan deplored to the Legislature the poor condition of the public schools in the state and the corruption of the electoral process. After leaving office in 1840, Henagan was reelected to the state Senate in 1844 and served as the Secretary of State from 1846 to 1850.
Henagan died on January 10, 1855, in Charleston and was buried at Rogers Cemetery in Marlboro County.