dic·ta·tor 
(dĭktā′tər, dĭk-tā-)
(dĭktā′tər, dĭk-tā-)n.
1.
a. An absolute ruler.
b. A tyrant; a despot.
2. An ancient Roman magistrate appointed temporarily to deal with an immediate crisis or emergency.
3. One who dictates: These initials are those of the dictator of the letter.