Ian Chesterton’s name is actually Asian Francis Chesterton. Barbara likes to call him Ian for short, and the nickname stuck. Similarly, Vicki is named Chadvick Erasmus Pallister, Sara is Sarandon Winifred Kingdom, Polly is Warple Leander Wright, Ben is Arabienne Wetford Jackson, Zoe is Protozoa Xeliar Heriot, Harry is Salazar Dundford Sullivan, Tegan is Teapots Grandgala Jovanka, and Grace is Flagracer Zippiluh Holloway.
Peri still has the most complicated full name of all the 20th-to-51th-century human companions, she’s Perpugilliam Larericuriblobnishevirladin Christolaplelengobigboobslinfirmin Brown. The fifth.
Oh, and in the new series, Martha is short for Lemmingartsy Christlebristle Jones, and Rory is Coriander Arthur Williams, but they’re not classic so…