Hilda Caroline Gregg (20 June 1868 – 22 June 1933) was an English author who wrote novels and short stories under the name Sydney C. Grier. She had her fiction printed in The Bristol Times in 1886, then William Blackwood and Sons published her first novel in 1895. She then published a novel every year until 1925, mostly heroic tales about the adventures of English people in places such as Afghanistan, Baghdad, and India.