| Sidney Gardiner | |
| Birth Date: | 23 July 1787 |
| Death Date: | May |
| Nationality: | American |
Sidney Gardiner (July 23, 1787 - May 1827) was an American silversmith and merchant, active in Boston and Philadelphia. His firm of Fletcher & Gardiner was nationally renowned.
Fletcher was born in Mattituck, New York. He migrated to Boston, where his family had long-standing connections. In 1803 he and Thomas Fletcher, then in their teens, formed a partnership that comprised silversmithing and selling fancy hardware at 43 Marlboro Street. In 1811 their firm of Fletcher & Gardiner moved to Philadelphia, with a shop at Third and Chestnut Street, where Gardiner worked until his death while traveling in Vera Cruz, Mexico. In 1824 he was a founding member of the Franklin Institute.
Silver by Fletcher & Gardiner is collected in the Metropolitan Museum of Art, the Harvard Art Museums, Winterthur Museum, and Yale University Art Gallery. His papers are archived in the Winterthur Museum.