How to get username in AWS Cloudformation template file?

I have resources defined in my Cloudformation template file with tags defined like so:

  "Properties": {
    "Tags": [
      { "Key": "Environment", "Value": {"Ref": "Environment"}},
      { "Key": "Hello", "Value": "World"}
    ]
  }

My IAM username is my.name. I would like to add a key named Creator with value username. How can I do it?