Hi,

A quick question: Has anyone been granted a TOEFL waiver before at HLS?

It's rare. They will only consider your request if you've had at least two years of full-time study in English at university. Even if you do, it's not likely that they'll grant the waiver. Unless you're some kind of Olympic medalist or have something else extraordinary about your profile that would make you very valuable to them as part of the cohort.