You can find monologues in drama online. Select under type "monologue."
Includes the following collections: Core Collection, The Donmar Shakespeare Trilogy on Screen, The Hollow Crown, L.A. Theatre Works, National Theatre Collection 1-3, Nick Hern Books Modern Plays, Playwrights Canada Press, The RSC Live Collection, Shakespeare's Globe on Screen 1 and 2, Shakespeare's Globe to Globe Festival on Screen 1 and 2, and TCG Books Play Collection.