Worldwide, Mattsen (Mattsen 
) is an extremely rare masculine first name. Much more frequently, Mattsen is the last name as well as the forename.
Mr, John, Jody, Jean, Todd, Teri, Nils, Erik, Emma, Evan, Finn, Wini, Maria, Sarah, Shari, Shane, Shawn, Susan, Steve, Scott, Alice, Allen, Jane, Lynn, Lora, Lori, Sã, Ann, Bob, Kim, Ron, Deb, Dan, Jay, Jon, Tom, Annie, Mary, Mike, Chad, Kara, Karl, Paul, Ruth, Ryan, Dale, Gary, Leon, Mark, and Anita