Frank Addison Knight (October 17, 1908 – May 14, 2012) was an arborist from Yarmouth, Maine, United States.

One of his most prominent roles was as the tree warden for "Herbie", an American elm that stood in Yarmouth for over 200 years.

[1] Knight's efforts to extend the tree's life brought him international attention.

[7] He graduated North Yarmouth Academy in 1925, and later served on the school's board of trustees for over 25 years.

His early career saw him working in woodlands in upstate New York and northern Maine.

Now Herbie will take good care of Frank," said Deb Hopkins, who succeeded Knight as Yarmouth's tree warden in 2006.