What are some good usernames using the name maddie?

Depends on your interests, birthday, favorite color/singer, etc.

For example, if you like the color purple and you were born in 1990, you could be purplemaddie1990. Or if you like swimming, you could be maddieswims1990. Anything is possible. If you find those too long, just use your age (purplemaddie21, etc.)

Using this theory I could be pinkcarlie1994. Use your imagination.