The lieutenant governor of Missouri is the first person in the order of succession of Missouri's executive branch, thus serving as governor in the event of the death, resignation, removal, impeachment, absence from the state, or incapacity due to illness of the governor of Missouri. The Lt. Governor is elected separately and can be of a different party than the governor.
List of lieutenant governors of Missouri
https://en.wikipedia.org/wiki/List_of_lieutenant_governors_of_Missouri