interjectorn.

/ɪntəˈdʒɛktə/Etymology: agent-noun from Latin interjicĕre to interject v.
the mind > language > speech > interruption > [noun] > one who interrupts
1891 3 June 6/1 The interjector always gets the worst of it in an encounter with an old parliamentary hand.
This entry has not yet been fully updated (first published 1900; most recently modified version published online March 2018).