Caubac Alcatraz

In Tsukihime:

Alcatraz is a magus who became a vampire through his magical research. He is an old friend of Kischur Zelretch Schweinorg, and he was one of the people present for Arcueid Brunestud's birth eight-hundred years ago. He only met her that one time, but he left a lasting impression on her. He has been missing for over a century, and it is unknown to others if he is still alive.

In Tsukihime remake:

Prior to becoming a vampire, Caubac was a member of the Holy Church. He lost his heart thanks to the actions of Crimson Moon shortly before the transition to AD, but Crimson Moon also saw potential in him and transformed him into an Ancestor. Around the year 1000 AD, he completed the Holy Scripture Triten. Caubac is called one of the "three idiots" who make up Kischur Zelretch Schweinorg's tea-drinking companions.

In Mahou Tsukai no Hako:

Mr. Cellphone is a Mystic Code through which Caubac Alcatraz interacts with the outside world.