Sydney Vacher was an English architect.
Vacher was born in Kensington, the son of Thomas Brittain Vacher (1805–80). He entered a partnership with Evelyn Hellicar in the late 1880s. Their office was at 35 Wellington Street, The Strand, London. Together they won the competition to design the Valley Primary School, Shortlands, Kent in 1889.
He died at Portsmouth, aged 80.