The X-Man in question is Anole, a comparatively new addition to the mutant ranks, so you may not recognize him. I'm assuming he's standing triumphantly but I suppose he might just have been taking in the view when a giant great head came smack down on top of him.
ALl in all a nicely executed scene by Mr. Xenomurphy.
Source: MOCPages — Anole vs. Sentinel
LEGO X-Men — Sentinel Head by Eoghann Irving, unless otherwise expressly stated, is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.