The Colbys were residents of the holographic 19th century Irish village Fair Haven.
When Mary Mulchaey fell into a well near Ballahick Farm, Milo ran to the Colbys to get help, but by the time they returned, Mary was safely in a meadow talking with Katie O'Clare. This, combined with other incidents, led to a distrust among the villagers of newcomers to Fair Haven, the USS Voyager crew. (VOY: "Spirit Folk")
This family was only mentioned in dialogue.