That is if you'd like them to be personal. You could stick with default Shep, but who wants to do that?
What Are Face Codes?
If you miss your old Shepherd and want their actual face in your game, Mass Effect Legendary Edition has you covered.
It won't take their personality or decisions with them but it will take all their looks with you, ready to take on a new adventure.
It won't be entirely perfect, as the team had some issues bringing forward the old code, but they've done a pretty good job at modernising their face creator.
How to Use Face Codes in Legendary Edition
This answer all depends on the game you're taking it from. Let's start with the basics. If you want to import your old face, you need to have access to that old save file or a screenshot of your face code.
Unfortunately, with Mass Effect 1, you have to bring your character's face to Mass Effect 2 or 3 to get your face code. Once you've done this, you should be able to find it in the squad menu on the left-hand side. Write down the code (be warned, it's a long one).
From here, you can shut down your old game (you won't need this anymore) and boot up the legendary edition. Start your game and go into the character creator at the very start. At the bottom of the page, you will see the option to type in your code.
Type in that long code and your old Shep will pop up in front of you. You may need to make some changes to get them just right but it will give you a good base to start from.