Alex

Alex is a character who debuts in the Game Boy Color version of Mario Tennis. His doubles partner is Harry. In the game, everyone at the Royal Tennis Academy is surprised at Alex's very fast rise in the club ranks by getting into the varsity team by beating the fourth placed Bob, which he does days after being instated. He beats Emily on the way to the final against Factory's A. Coz and wins easily. After hearing of the newest tennis star, Princess Peach invites Alex for a match against Mario. In the Nintendo 64 version of Mario Tennis, he is a transferred character and can be played in this version, though not in its Virtual Console port.

In Mario Tennis: Power Tour, Alex holds the distinction of being the Academy's best ever player and is still the only one that has challenged Mario before. However, he has retired from competitive tennis and has become the Academy's head coach. Alex develops a training regimen for not just the players, but also for the other coaches, based on the Power Shot that he saw Mario use. At the start of the game, Alex loses the match against Mario, who is wearing a mask to hide his identity. He states that he is surprised that Mario came back for a rematch and wonders when he'll be seeing him again. When Clay or Ace are about to leave to the Mario World after winning the Island Open, Alex tells them a bit about his experience against him and expects the player to beat the plumber. When the player beats the Master level of the Tennis Machine, Alex, along with Nina, come to congratulate the player. Nina proceeds to tease Alex, and reveals that Alex became afraid of the siren that sounds after beating the Tennis Machine.