Joel Tennyson made his first appearance in "My Big Fat Alien Wedding". He is Grandpa Max's nephew and Ben, Gwen's cousin. In addition, he is a member of The Plumbers like his uncle, Max. He made a relationship with an alien species known as the named Camille Mann. There has been a history of Sludgepuppies and The Plumbers at war for many years. Both Joel and Camille have hopes that there will be truce between each other after they engage. Unfortunately, there were wedding crashers and they were Mr. and Mrs. Mann, Camille's parents. Afterwards, the marriage continued successfully thanks to the help from the Tennysons.
Joel Tennyson has made only one appearance in the Ben 10 Series.

Joel Tennyson's First Appearance
Big Fat Alien Wedding

Joel Tennyson's Last Appearance
Big Fat Alien Wedding

see also: Tennyson Family