Geni offers a family tree of Charlemagne that spans 80 generations. Backer Dirks offers a family tree of Frankish kings that includes Charlemagne.
The family tree from Geni begins with Charlemagne Patricius Romanorum, who lived from 742 until 814. The next generation includes Pepin II le Bref and Bertrade II de Laon. The very last generation includes King Laomedon van Troye and Strymo van Troye. At Backer Dirks, the family tree starts with Arnulf of Metz and includes about five more generations until it reaches Charlemagne. The family tree ends with Gerrit van Culemborg and Ernst Taets van Amerongen. Some other places to find Charlemagne's family tree include the website of Scott P. Pavelle and the Library of Halexandria.