Neutral:
* Interrupter: This is the most neutral term, simply describing the act of interrupting.
* Intruder: This emphasizes the unwanted nature of their intrusion.
Informal:
* Butt-in: This is a more informal and direct term.
* Conversational Hijacker: This is a more playful and lighthearted term.
* Chatty Cathy/Chatty Kathy: This is a playful term for someone who talks a lot and interrupts often.
Negative:
* Interrupting: This implies that the person is being rude.
* Overbearing: This suggests that the person is domineering and tries to control the conversation.
* Loudmouth: This implies that the person is talkative and doesn't respect others' space.
* Know-it-all: This suggests that the person always wants to be the center of attention and shares unsolicited opinions.
The best word to use depends on the context and the tone you want to convey.