Frederick Newton Wier (July 4, 1861 – October 31, 1936) was an American politician and lawyer who served as district attorney of Middlesex County, Massachusetts from 1893 to 1902.

Weir was born on July 4, 1861, to Newton John and Caroline (Peabody) Wier in Lowell, Massachusetts.

He studied in the office of J. M. Marshall in Lowell and graduated from the Boston University School of Law in 1887.

[2] In 1891, Wier represented Charles J. Tighe, who was charged with the murder of Peter E. Johnson, a member of the Wampanoag Tribe of Gay Head.

The firm of Trull, Wier, & O'Donoghue was counsel for the Boston and Maine Railroad, Eastern Massachusetts Street Railway, and the Middlesex Safe Deposit & Trust Company.