"Magician" (マジシャン Majishan) is an archetype of cards solely supported by the manga effect of "Magician's Circle" and "Magicians Unite". "Magicians" don't have a specific focus nor do they have any relations.
During the original Duel Monsters, "Magician" cards were part of the class type known as Magic User. Each Magic Users come with a certain Alignment like Black Magic, White Magic, Demon Magic and Illusion Magic. The different types of Magic User have strengths and weaknesses depending on which type of Magic User they are battling.
The most notable Magic User was the "Dark Magician", as many cards that were used on "Dark Magician" in the manga and anime, have the kanji 「魔術師」, 「黒魔術師」 or 「黒魔族」 in the card text. Cards like "Magical Hats", "Magic Cylinder", "Magic Formula" and "Magical Dimension" have the kanji 「魔術師」 "Magician". Cards like "Mystic Box", "Nightmare's Chains" and "Dark Magic Curtain" have the kanji 「黒魔術師」 "Dark Magician". Lastly, the cards like "Dark Renewal" and "Thousand Knives" have the kanji 「黒魔族」 "Black Magic User". The "Dark Magician" was used by Yugi Muto, Yami Yugi and Arkana.
During Dawn of the Duel arc in the Yu-Gi-Oh! manga/anime, another "Magician" cards was introduced which was the "Silent Magician". The "Silent Magician" was different from the "Dark Magician", as they didn't display any Alignments nor use any Magic User cards. Instead, they rely on LV and ATK increase, each times the opponent draw a card. The "Silent Magician" was used by Yugi Muto.
In the Yu-Gi-Oh! 5D's anime, Vizor uses the "Magician" cards, T.G. Cyber Magician" and "T.G. Wonder Magician". Vizor will often try to Synchro Summon "Wonder Magician" after using "T.G. Rush Rhino" and "Cyber Magician". After "Wonder Magician" is Summoned, Vizor will Summon "T.G. Power Gladiator" to Accel Synchro Summon "T.G. Blade Blaster".
In the Yu-Gi-Oh! ZEXAL anime, Vector uses the "Magician" cards, "Number 104: Masquerade" and "Number C104: Umbral Horror Masquerade". Vector will use the anime effect of "Masquerade" to negate card effect, inflict damage and send one card from the Deck or hand.