J is the tenth letter in the Alphablocks gang.
She is a blue and white block including an orange 'beak', since she thinks she is a blue jay bird.
J is cheerful and a big dreamer, thinking she can fly like a real jay birds do.
- "Jaybird! I'm a jolly J."
- "Jolly nonsense."
- "Jumping juggernauts!"
- "Jumping jellyblocks!"
- "Jumping jumbos!"
- J appears in 17 episodes of the series.
- J's letter means 18/19 in Vigesimal.