Admiral Han 'Gerrel Vas Neema is a Quarian Admiral who appears in Mass Effects 2 and 3. Though seeming like a friendly, good-natured, and honorable individual, he is in fact a raging xenophobe who desires to reclaim the Quarian homeworld Rannoch no matter the moral cost. He is voiced by Simon Templeman.
Admiral Han 'Gerrel is an old friend of Tali and her father Rael 'Zorah, and served with the latter back before the two's pilgrimage. Disobeying orders, the two had pulled off a daring attack against pirates that had them hailed as heroes by everyone except their superiors, who condemned them as idiots.
By the time of the Mass Effect games, Han 'Gerrel has become obsessed with reclaiming the Quarian homeworld from the Geth, who he views as pure evil monstrosities that must be exterminated at all costs, also seeing absolutely nothing wrong with the Quarians' earlier attempted genocide against their creations. Though friendly and supportive to Tali during her trial, talking to him reveals quite clearly his extremist views.
Han 'Gerrel's fanaticism comes to a disastrous head in the third game, where against the advice of Tali (who now knows from Legion that the Geth are by and large peaceful and not malevolent) he convinces the rest of his people to go to war with the Geth in a bid to reclaim Rannoch. Desperate to avoid extermination, the Geth join the Reapers in response even though this will cost them their free will, much to Legion's dismay. When Commander Shepard and Tali board a Geth Dreadnought, Han 'Gerrel attempts to destroy it from afar even though they are still onboard, which can prompt Shepard to late punch him in retaliation.
The Geth-Quarian war comes to a head later, where Han 'Gerrel is determined to continue his insane war through to the end, even if it condemns his entire species. However, Shepard can potentially bring about a peaceful resolution, which Han 'Gerrel will ultimately accept. Alternatively, Shepard can choose to condemn either the Quarians or the Geth to extinction.