The memorial honours Rick Rypien, who took his own life last year after battling depression.
Following the Bieber concert at the arena Wednesday night, the fan wrote "J.B. concert 2010" in black felt on the memorial, and signed it using a female name.
The graffiti triggered a backlash on Twitter from hockey fans who say the girl should be ashamed, should apologize and clean up the memorial.
Fans eventually found a Twitter account that allegedly belonged to the graffiti artist and started threatening her until the account was deleted.
Others on Twitter spoke out against the threats, saying bullying sends the wrong response. (News1130,CKNW)