Have written a suicide note for my family detailing the different people I need them to tell (mostly online people), my wishes for disposal of remains, and the usual emotional stuff.
Have written shorter suicide notes for three of my friends which I intend to email to them on a delay. For some of my other friends, who I intend to send money to before I die, I have written a short note which will send in WhatsApp just to explain that this was not a mistake.
Finally, if I kill myself in a hotel room then I will probably leave a note for staff, paramedics, police, and the coroner.