Simeon Selby Pennewill (July 23, 1867 – September 10, 1935) was an American farmer and politician from Dover, in Kent County, Delaware.

The elder Simeon was one of the larger peach growers and owned the land that later became the town of Greenwood.

Simeon, the younger, was educated at Wilmington Conference Academy, now Wesley College in Dover.

The Delaware General Assembly at this time approved the sale of the Chesapeake and Delaware Canal to the Federal government, and passed the Boulevard Corporation Act, which provided the legal authority for T. Coleman du Pont to begin to build his privately funded highway the length of the state.

He also made a controversial appointment to his elder brother, James Pennewill, the position of Chief Justice of Delaware.