|Played By||Sara Canning|
When Lois infiltrated the Luthor Mansion dressed a French maid to look for information on her cousin Chloe, Tess found her and asked Kat and a bodyguard to escort Lois out of the building. She later brought Tess all the information that an Arctic excavation team had found on the whereabouts of Lex Luthor. She handed over a picture of Clark Kent's footprint and a briefcase containing the glowing Crystal of Knowledge.
When Tess has Clark called into her office at the Daily Planet, she asked him about Lex before he left. Kat entered and offered to have Clark followed to see if he knows anything about Lex. Tess declined, saying that she would watch Clark personally.
- Kat's name has yet to be revealed as she hasn't been directly spoken to. However, casting sides, as well as an interview with Cassidy Freeman, indicate her name is Kat.
- Tess Mercer had another assistant named Eva Greer.
- Her role with Tess is similar to Gina's role with Lex being an Executive Assistant.
- Sara Canning starred as Jenna Sommers on the CW series The Vampire Diaries alongside Paul Wesley (Lucas Luthor), Cassidy Freeman, and Ian Somerhalder (Adam Knight).