December 1 (announced last week)
Signed RHP Felipe Paulino to a minor-league contract and invited him to Spring Training
December 7
December 9
St. Louis Cardinals claimed LHP Jayson Aquino off waivers
December 10
San Diego Padres selected RHP Josh Martin in the Rule 5 Draft (major-league)
December 11
Signed OF Robbie Grossman to a minor-league contract and invited him to Spring Training
None of these players are guaranteed to make the Opening Day roster, or even play a game with the Indians, but there's a good chance that at least one of these players will make a meaningful contribution.