Cyclops's older brother, recruited out of a military prison, who fires plasma out of his chest and cannot aim it.
Alex Summers can generate plasma discs from his body, and he is Cyclops’s older brother and a former member of the X-Men. Lucas Till plays him across three films.
The relationship is the odd part of the series. Alex is introduced first, decades before Scott, so in this continuity the famous Summers brother is the one who arrives second and does not get told much.
Minor spoiler
When Apocalypse takes Xavier, Havok attacks and blows up a generator and the school with it. He is too close to the blast for Quicksilver to reach him, and he dies.