Sam Tucker is the deceased father of Cale Tucker in Titan A.E.. It is unknown why he never even spoke of his wife, so it is possible that he and Cale's mother either got divorced or he got widowed. He was the one that sent Cale away on the Titan when the latter was five years old during the destruction of Earth by the Drej under Queen Drej's orders.
"Once in a great while mankind unlocks a secret so profound that our future is altered forever. Fire, electricity, splitting the atom... At the dawn of the 31st century we unlocked another. It had the potential to change humanity's role in the universe. We called it the "Titan Project," and it was a testament to the limitless power of the human imagination. Perhaps that is what the Drej feared most, for it brought them down upon us without warning and without mercy. Cale, that day, the day that the Drej descended from the sky, the only thing that mattered was keeping you safe".