Nestor
Debut: The Secret of the Unicorn
When Captain Haddock gained Marlinspike Hall he also gained
the faithful butler Nestor, and the series gained a very colourful, if
a little shy, character. 
When we first meet Nestor in The Secret of the Unicorn, he is the butler of the nasty Bird Brothers, who own Marlinspike Hall. He aids them in their capture of Tintin, but Hergé makes us aware that he is only doing so out of loyalty to his employers. For this reason, Tintin is ready to forgive him at the end of the book, and he becomes a faithful friend and servant to Captain Haddock at the end of Red Rackham's Treasure.
Nestor is a strange character. Although in the service of Captain Haddock, he remains quietly aloof from the old sea-dog, and only deigns to speak to him when he is spoken to. He is, on the other hand, quick to come to his masters aid in a crisis, although he often appears spineless, such as in the opening sequence of The Calculus Affair.