As a landlord you don’t have any control about the tenant having visitors. By law, the tenant does not have to inform the landlord in advance about their visitors and it is not considered trespassing when anyone is visiting the tenant, even when they stay overnight. A tenant has the right to have anyone visit as long as they are not disturbing anyone else in the house. If they are making excessive noise especially during late night hours then you can do something in this case. You should speak to the tenant first and ask that they refrain from making noise late at night.If the problem continues then you have the right to serve them with a legal notice based on the reason that they are interfering with your reasonable enjoyment of the premises. If a landlord lives in the same building that has 3 or fewer residential units a Form N7 may be served in this case, visit the Landlord and Tenant Board’s website at https://tribunalsontario.ca/ltb/forms/#landlord-forms to obtain the forms and more detailed information.