Little Brother, Big Trouble: A Christmas Adventure (also known as Niko 2: Little Brother, Big Trouble, or simply Niko 2) is a 2012  animated comedy/adventure film. It was produced by Finnish studios Anima Vitae and Cinemaker OY, with co-producers Ulysses (Germany), A. Film (Denmark), and Tidal Films (Ireland). The  animation was produced in Finland, Germany and Denmark, with post-production carried out in Ireland. It is the sequel to The Flight Before Christmas and was written by Hannu Tuomainen and Marteinn Thorisson, and directed by Kari Juusonen and Jørgen Lerdam. It was released in Finland on 12 October 2012. Anima Vitae and Cinemaker OY were nominated for Cartoon  Movie Tributes 2013 in the category "European Producer of the Year". Like its predecessor, it is among the most expensive Finnish films ever produced.

The film was followed by a sequel, Niko: Beyond the Northern Lights, which was released in October 2024.