Lawrence Gustave Murphy (1831 – October 20, 1878) was an Irish immigrant to the United States, Union Army veteran, Grand Army of the Republic member, Republican Party ward heeler, racketeer, Old West businessman and gunman, and a main instigator of the Lincoln County War.

Murphy was Irish Catholic born in County Wexford, Ireland, and as a young adult moved to the United States.

This, however, was common practice at the time and, in Santa Fe, the capital of the Territory of New Mexico, "a specialized legal profession had grown up around the manipulation of title" to “old Spanish and Mexican land grants.

As a member of the Republican Party political machine known as the Santa Fe Ring, Murphy also wielded considerable power over law enforcement, as Lincoln County Sheriff William J. Brady lived on a cattle ranch that he had purchased using money borrowed from Murphy and Dolan's bank.

On February 18, 1878, while Tunstall was alone, he was shot and killed by Jesse Evans, William Morton, Frank Baker and Tom Hill, likely under the orders of Dolan.

As the Sheriff lay dead, Billy the Kid ran from the place of ambush in order to remove the arrest warrant from Brady's pocket.