Rihanna -- Stalker Arrested ... For Creepy Note Threats

A homeless man was arrested in New York for stalking and harassing Rihanna ... by delivering super creepy hand written notes to her home.

Kevin Mcglynn was allegedly caught on surveillance video 3 separate times this month ... delivering the notes calling her a bitch and threatening to bum rush her home.

The New York Daily News reports he also allegedly sent at least 4 letters to her California home.

On his 3rd visit earlier this month -- the homeless man dropped his benefits card in the singer's SoHo building ... leaving his address, so cops easily tracked him down.

Mcglynn claimed in court Rihanna, Jay Z and Kanye West jacked his "material."