No, Minecraft usernames cannot have spaces. When you create a new Minecraft account, you must choose a username that consists of a single word, and you cannot include any spaces or special characters in your username. This means that you will need to choose a username that is made up of letters and numbers only, and you will not be able to use any spaces or other special characters in your username. It's also worth noting that Minecraft usernames are case-sensitive, so you will need to be careful to enter your username exactly as you created it when you log in to the game.