Ellis Spear (October 15, 1834 – April 3, 1917) was an officer in the 20th Maine Volunteer Infantry Regiment of the Union Army during the American Civil War.

Spear was born on October 15, 1834, in Warren, Maine[1] where he grew up on his family's farm and attended a Presbyterian church Sunday School.

During the second year of the Civil War he became a recruiter and formed Company G of the 20th Maine Volunteer Infantry Regiment.

Exposure and discomfort in a hopeless adventure, defeat and humiliation, the loss we knew not how many of good men, discouragement, and increased distrust in the commanding general, all this was worse than the danger 1,000 times, and covered us with gloom.

[1] He was appointed brevet lieutenant colonel, to rank from September 30, 1864, for his service at the Battle of Peebles' Farm.