H.265 is also known as HEVC, which stands for High Efficiency Video Coding
H.265 is a new compression specification that is making its way into the industry as the successor of H.264. This makes it a candidate for a future video codec in WebRTC.
Like H.264, H.265 is royalty bearing and is governed by the MPEG-LA, although exact patent holders and costs are yet to be organized.
H.265 is assumed to be more CPU intensive than H.264 with better compression results. Its main “competitor” in WebRTC is VP9.