The phrase "one of the old guard" refers to a person who has been part of an organization or group for a long time and is resistant to change. There are several synonyms that can be used to describe such individuals, including stalwart, loyalist, traditionalist, conservative, and diehard. A stalwart is a dependable and committed supporter, while a loyalist is someone who remains steadfast in their allegiance. Traditionalists are known for valuing and preserving customs and practices. Conservatives are resistant to change and adhere to traditional values. Diehards are people who maintain a steadfast and determined attitude regardless of circumstances. These synonyms convey the unwavering commitment of individuals who are part of the "old guard".