Udo

You can't see me!

_{This character has no official visual representation in any Transformers product or media... yet, at least.}

Udo (ウド) is Hiroyuki Otoboto's dear friend.

So dear that Hiroyuki thought he was dead while Udo was on vacation.

Fiction

Animated cartoon

Actor: Hiroyuki Amano

Observing Hiroyuki, his father, chatting on his cell phone, Tatsuya Otoboto flashed back to a week earlier, when they were playing with their toys and bumped into Yūka Otoboto. Yūka, the daughter of Hiroyuki, gave him a letter from Udo, who Hiroyuki thought had died three years ago. Secret of the AllSpark

After Hiroyuki "transformed" his food, Yūka gave another letter from Udo. As it turned out, Udo wasn't dead, just in Hawaii. The Great Sound Wave Operation

Notes

While not outright stated, "Udo" is almost certainly a reference to Udo Suzuki, the partner of Hiroyuki Amano, who plays Hiroyuki Otoboto in the comedy duo Kyaeen.