Henry Highland Garnet was an African-American abolitionist, minister, educator, and orator. He and his family escaped to New York from slavery in Maryland, in the early 1820's. 
Henry was born on December 23rd 1815, in Kent county, Maryland. His parents are named George and Elizabeth. 
Henry's paternal grandfather, known as Joseph Trusty, is said to be a member of the West African Mandigo tribe, captured, transported and sold to Colonel William Spencer of Maryland. Joseph Trusty's wife, who had crossed the ocean from the African continent to America on the same slaveship, is most probably Henry's grandmother. 
When Henry was about 8 years old, Colonel Spencer, who was still slaveholder of the Trusty family, died. Fearing they would be inherited by a cruel owner, Henry's mother (described as "a woman of great energy") and father conceived a plan to escape. In all, eleven members of the Trusty family fled to Wilmington, Delaware with the help of the Underground Railroad.  Indeed Maryland court records confirm that "all the negroes belonging to the estate of William Spencer, appraised at $1200, absconded soon after his death, and were finally lost, though legal measures were taken to recover them, by his executor, Isaac..."
Henry's family later moved to New Hope, Pennsylvania, and then to New York. His father George was a shoemaker.  It is unknown at this time when the surname Garnet was first adopted in the "Trusty" family.
Henry Garnet was one of a handful of black students educated at the Noyes Academy in Canaan, New Hampshire around 1835. During his studies an armed racist mob gathered to attack the school. It is said that he fended them off with rifle fire, and that he met his wife Julia Williams on that day. 
Henry and Julia had three children: Mary, James and Henry. 
He died, at the age of 66, on February 13, 1882 in Monrovia, Montserrado, Liberia. He is buried at the Palm Grove Cemetery in Monrovia, Montserrado, Liberia. 
Is it possible the name Garnet was taken in honor of Thomas Garrett , a leader of the Underground Railroad who had helped the Trusty family?
Biography needs work on Henry's career, the loss of his first wife, his second marriage, his move to Liberia.
↑ "United States, Freedman's Bank Records, 1865-1874," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:NSYX-15J : 9 March 2018), George in entry for Henry Highland Garnet, ; citing bank New York (City), New York, United States, NARA microfilm publication M816 (Washington, D.C.: National Archives and Records Administration, 1970); FHL microfilm 928,585.
↑ "United States Census, 1850," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MCBB-6PD : 4 April 2020), Henry H Garnett, Seneca, Ontario, New York, United States; citing family 747, NARA microfilm publication M432 (Washington, D.C.: National Archives and Records Administration, n.d.).
"United States Census, 1880," database with images, FamilySearch (https://familysearch.org/ark:/61903/1:1:MZ6S-HH3 : 7 September 2017), Henry Garnet, New York, New York, New York, United States; citing enumeration district ED 165, sheet 568B, NARA microfilm publication T9 (Washington, D.C.: National Archives and Records Administration, n.d.), FHL microfilm 1,254,874.