U is the 21st letter in the Alphablock gang.
U is voiced by David Holt in the UK.
- U is a blue Alphablock who wears a blue hat, glasses and shoes.
- U often runs away from Q.
- U favors words prefixed with un-, especially if they have pessimistic overtones ("unhappy", "unfair", and the like).
- Alphablocks (first appearance)
- Alphalympics (sound only)
- Rainbow (sound only)
- Little Red N
- The End
- Plusman (sound only)
- Alphabet (stays as digraph UR)
- Birthday Girl
- Tween Scenes (as a toy)
- Band Together
- The Wonderful Wizard of Az
- Letters to Santa
- Making Friends
- Crossover (image only)
- The Case of the Missing Blocks (last appearance)
- His “long vowel” episode is Blue.
- He has a one-sided relationship with Q.
- U is often unlucky, as seen in episodes like Up.
- The color of this Alphablock is similar of the box in the episode Odd, but the box is a lighter color than him.