Schemer (noun)

1. A person who schemes; a plotter.
2. A person who devises plans or plots to achieve a goal, often in a devious or underhanded way.

Origin:

From middle english schemeren, from old english sceamrian, from proto-germanic *skaim(m)ērian (compare dutch schimmeren, german schimmern), from proto-indo-european *(s)kei- ("to shine, glea.m")

Examples:

1. The schemer was always looking for a way to gain an advantage.
2. He was a schemer who always had something up his sleeve.
3. The schemer was exposed and his plans foiled.
4. He was known as a schemer in the office.
5. The schemer"s plan was to steal the company"s confidential information.