What is the guy on silent witness called?

You are likely thinking of Professor Leo Maxwell, played by David Burke. He is a forensic pathologist and one of the main characters on the British television series Silent Witness.

However, it's worth noting that the series has had a few other male forensic pathologists over its run, including:

* Dr. Sam Ryan, played by Amanda Burton (1996-2004)

* Dr. Thomas "Tom" Linley, played by William Gaminara (2004-2007)

* Dr. Nikki Alexander, played by Emilia Fox (2004-present)

If you can provide more context, like the specific episode or season you're thinking of, I may be able to help you identify the specific actor you're looking for.