Most grad schools will strongly recommend that you ask at least one academic for a letter. This can be a professor, a TA, or a lecturer. Depending on the program and your career progression, it may also be appropriate for you to submit a letter from an employer.
You should generally only ask for letters from people who will write glowing reviews for you. Some people argue it’s worth getting a letter from a well-known academic, even if they don’t know you that well. Generally, it’s more important that someone can speak highly and extensively about you than having a well-known person write something lukewarm.
Depending on your application, you might also want to ask for letters that highlight your multiple dimensions. For example, your athletic coach can write about your discipline and leadership skills. A professor can write about your intellect and curiosity. These types of well-rounded letters will make you a more compelling applicant overall.
When you decide who to ask, you should give them ample time to write. At least a few weeks of notice is courteous. Remember to thank your letter writers and let them know if you’re admitted!
