Conjurer
An Conjurer is a form of Specialist Wizard in Dungeons & Dragons. As their name suggests, these wizards focus their attention on the magic school of Conjuration, the art of calling forth beings from other planes to serve their bidding. These are minion-master wizards, and one of the styles traditionally most hated by DMs and other players alike; not only can their personal army of summoned goons make combat go on for ages, but their ability to command the magical powers of the creatures they summon makes them hugely overpowered. A classic example is the Conjurer summoning a creature that can then summon other creatures, leading to an exponential increase in minions - and this is one of the lesser ways they can abuse its potential.
Ironically, Conjurers are the only specialists other than Necromancers who seem to get generally perceived as evil, mostly because of the cultural archetype has them summoning fiends from the Lower Planes. In fact, Advanced Dungeons & Dragons 2nd edition had a Necromancer kit called the "Undead Master" who strove to be an archetypical "pulp style" Evil Wizard by basically being a triple-classed Conjurer/Enchanter/Necromancer.
5th Edition's Arcane Tradition
Conjurers, as you might expect, focus on buffing up their conjuring skills. Minor Conjuration (level 2) lets them immediately conjure up any small item they need whenever they want. Benign Transposition (level 6) lets the conjurer teleport 30 feet or tele-trade places with a creature of their choice within that distance; this can normally only be done once per day, but a Conjuration spell lets them refresh that timer automatically. Focused Conjuration (level 10) means they no longer need to take concentration checks as a result of taking damage, so long as they're concentrating on a Conjuration spell. Finally, the humble Durable Summons feature (level 14) grants +30 temporary hitpoints to all summoned and conjured creatures.