Wow this was much, much harder than I thought, hence why it's taken me to the end of January to decide. They are all so, well...and Bertie Carvel made hottie of the month twice...but it's not him. Sorry Bertie.
I've chosen Peter Rykov, from Cheek By Jowl's Russian Measure For Measure (which also made my favourite theatre list). The reason is I still remember the feeling, the slightly breathless/giggly feeling I had at the end of the play. And also, of all my hotties from 2015 he's the one I'm least likely to see on stage again so I think I should honour him while I can. Here's his hottie entry and the rest of the hotties from 2015.