digresser
/ˈdɪɡrɛsər/Definitions
1. noun
A person who digresses, especially one who frequently goes off the subject in conversation or writing.
“The lecturer’s tendency to become a digresser made it difficult for the students to follow her lectures.”
2. verb
To cause or induce someone to digress, especially in conversation or writing.
“The provocative question digressed the discussion from the main topic.”