Obviously YES. It's technically stealing.
Yes, it is illegal to use another person's cell phone without permission since that is a form of theft; in principal it is illegal even to use another person's coffee cup or pencil without permission, although such offenses are very petty and it is doubtful that the police would be willing to investigate them. If the unauthorized cell phone use resulted in a large expense for the cell phone owner, that is a more significant crime.
If they were unused checks and you had not signed them, then it is definitely Illegal. Using another persons check without his/her signature and permission is an illegal activity. Even if it is the spouse using your check.
If you view or alter any files on a computer or online without permission, you are breaking the law
Yes, it is illegal to tow someone else's car without their permission.
My permission.
It is generally not illegal to take screenshots without permission, but sharing or using those screenshots without permission may violate privacy or copyright laws.
Yes, it is illegal to send unsolicited emails without permission, as it violates anti-spam laws.
Downloading copyrighted material without permission is illegal and constitutes copyright infringement.
No, it is illegal for someone to enter your property without permission.
Yes, it is illegal to enter someone's house without permission. This is considered trespassing and is a violation of the law.
Yes, it is illegal to use a business dumpster without permission as it constitutes trespassing and theft of services.
Illegal immgrants/aliens. Asylum seekers. Occupying forces.
Yes, it is illegal to take someone's phone without their permission. This is considered theft and can result in criminal charges.