Can I use personal references?

Generally speaking, no, you should not use personal or character references when applying for jobs. They're just not as valuable as references that come from someone you've worked with professionally. Plus, it makes you look like you don't have many professional relationships or people in your corner.

On the other hand, if the job posting requires five references, and you've only got four professional ones, using a character reference for your final one is unlikely to hurt your chances. When considering good options for personal references, try to pick someone who has seen your skills at work (perhaps in an academic or volunteer environment) and is not a family member.