Charles H. Mason (1830 – July 29, 1859) was an American politician, the first Secretary of State for Washington Territory, and acting Governor for two and a half years while the territorial Governor, Isaac Ingalls Stevens, conducted railroad surveys and concluded treaties with First Nations tribes and confederations. In all he served four stints as acting Governor: Mason County, Washington was renamed in 1864 in his honor. Mason Lake, in that county, was also named for him.