I had heard of John Boyd Thacher before I saw the upper plaque: there’s a nice state park in the NY Capital District named after him. He was mayor of Albany twice, in 1886-88 and 1896-97. His father, George Thacher, was mayor 1860-62, 1866-68, and 1870-74. His nephew, John Boyd Thacher II (see the lower plaque) was mayor 1926-41.
While I’m at it, JB Thacher II’s successor was Erastus Corning 2nd, who was the mayor of Albany 1942-83. Erastus Corning, his great-grandfather, was mayor 1834-37.