Professor Tetti-Tatti is a character from Disney's 8th full-length animated feature film, Make Mine Music. He is the main antagonist in the segment, The Whale Who Wanted to Sing at the Met.
He is a ship captain intent on killing Willie the Sperm Whale, who he believes is nothing but a monster. Willie is actually a kind, gentle creature who only wants to become famous for his voice. Willie dreams of singing in the opera one day and practices for other creatures in the sea. When Tetti-Tatti and his crew finally find Willie, the crew is captivated by Willie's voice and begs the captain not to kill him. After Tetti-Tatti harpooned Willie, Tetti-Tatti's Sailors angrily jumped on their leader and started to beat up Tetti-Tatti, presumably to death.
Intent on the fact that he is still a monster, Tetti-Tatti kills Willie anyway. The narrator softens the blow by telling the audience not to be mad at Tetti-Tatti because he simply didn't understand, and also that Willie continues to sing in heaven.