Samuel Holt is a human scientist from Voltron: Legendary Defender and the father of Matthew Holt and Katie Holt. He and his son were part of Galaxy Garrison and sent to Kerberos on an exploratory mission with Shiro as their pilot, only for all three to end up being captured by the Galra Empire. After being imprisoned for a time on the ship of Commander Sendak, Sam was sent to a work camp while Shiro and Matt ended up in the Galra gladitorial arena. All three were declared dead in a crash by Galaxy Garrison, but Katie refused to believe it and eventually discovered that they had in fact disappeared without a trace. Her determination to find out what happened to them led to her posing as a boy named Pidge Gunderson and infiltrating Galaxy Garrison, ultimately leading to her joining Shiro as one of the Defenders of the Universe.