which timers are used by the arduino?

Hi, I’m working in a project and I need timer interrupts but as far as I know some of the timers in the arduino are being used for things like pwm, millis etc. I dont need long periods so even an 8 bit timer with a prescaler of 1024 should do the job, I’m using serial communication(2 serial ports) and PWM for servos, the board is an arduino mega 2560, is there any timer that I can use without messing around with those two functions?

Usually arduino on avrs configures the timers to do pwm on their respective compare pins (two per timer.). If you aren’t using ALL of the pwm outputs, you can probably reconfigure at least one timer.