Victoria was the daughter of Edward Waterfield who was killed in "The Evil of the Daleks" story. His final request was that the doctor take care of his daughter Victoria, so she became a crew member. Victoria was a shy teenage girl, but one possessed of a mighty weapon. She was a screamer! Several of the Dr Who companions were screamers, i.e. they walked around in a daze until a hideous, slimey alien snuck up behind them and tapped them on the shoulder, at which point they launched their high-pitched banshee scream that could be heard all the way to Gallifrey.
Victoria stayed with the TARDIS crew until the "Fury from the Deep" story. There she actually defeated a couple of seaweed aliens with the power of her scream, but at the end decided that she'd had her fill of adventures and left the crew.
Victoria was played by Deborah Watling. Born on Jan 2, 1948, Deborah was a child actress, and like other Dr Who actresses has had a long and successful career. Something nice is that Deborah hasn't forgotten the old Dr Who days and still goes to the Dr Who conventions.