Andrew Mercer (c.1859 - 1927) was a sailor and Labour activist from the Poplar area.
Born in Dunedin, New Zealand. By 1888, when he married Scottish-born Elizabeth Grant, he was living in Poplar.
He became branch secretary of the National Amalgamated Sailors' and Firemens' Union and treasurer of the Federated Trades and Labour Unions.
In March 1892 he was elected to the London County Council as a Labour Progressive Party councillor representing Tower Hamlets (St George's in the East). He served a single three-year term on the county council and was defeated at the next election in 1895.