Len Tennyson

Leonard Maxwell Tennyson is Gwen's brother, Ken's twin. Len is five minutes older than Ken. The day Gwen was born, Max made both twins promise to look after their baby sister. Len was sincere in his promise, Ken was half-hearted about it. Since that day, Len has always looked out for Gwen, who he lovingly calls Gwenny.

For his 16 birthday, Max gave Len a motorcycle. Len immediately began taking care of it, calling it Baby. When Max took Gwen and Ben across country, Len went along too. A rig attached the bike to the back of the Rust Bucket when Len didnt feel like driving along side. He, of course, took Gwen's side when she and Ben argued. Len was nearby when Ben found the Omnitrix. And when Vilgax's troops attacked, Len fought back, using a wrench as a weapon. Ben dubbed this "Wrench Fu", and the name stuck.

Len was always popular with the ladies, from the first day of high school. But the one who stole his heart was the one Gwen objected to the most, for obvious reasons: Charmcaster. For Len, it was love at first sight. He didnt care she wanted to hurt his sister. He was a man in love. About a year after the summer road trip, Charmcaster came looking for Gwen. She wasnt home, but Len was. They almost became intmate, until Len realized she had come to do Gwen physical harm. Len sent her away, heart broken.

Even after he reformed, Len was always butting heads with Kevin. Especially once Kevin and Gwen became a couple. Len frequently referred to Kevin's car as "a rolling junk heap", taunting him that "two wheels are better than four". This rivalry has subsided, thanks to Gwen's intervention.

After graduating from high school, Max arranged for Len to attend the Plumbers Academy, where he graduated with honors. Instead of becoming an active Plumber, Len chose reserve status, so he could remain on Earth, keeping his promise to keep Gwen safe.

During the pursuit of Aggregor, when Gwen went to get Charmcaster's help, old feelings resurfaced. Len was distracted by her presence. He knew that Charmcaster, or Charmy, as he often called her, was the only woman for him. Before he left Legerdomain, Len and Charmcaster kissed, with Len declaring his love for her, and that they would be together soon.