Every champion in League of Legends has an assigned class, with a limited number also possessing a secondary class. This class represents a defined set of patterns in player's behavior, responses and reactions to environment (including but not exclusive to enemies and own team). This may also include preferred item and ability paths, summoner spells, stats, runes or masteries.
The available classes are as follows:
As of V3.10, a champion's primary and secondary tags are now listed separately in the client's champion overviews. However, the in-client Summoner Profile and champion select only feature filters by primary attribute. The official champion list will use both primary and secondary indiscriminately when filtering by attribute.
On April 14th, 2016, Riot announced the intent to rework Champion Classes. The full list of champions was released on June 1st, 2016.  At this time, a small number of champions are unclassified.
Most notably, the changes include:
- The renaming of Assassins into Slayers, and Supports into Controllers.
- Adding subclass to all classes.
- Substantially less secondary classes.
- Disruptor subclass of Controller removed.
- Catcher subclass added to Controller, with a substantial rearranging of "support" champions.
- Unclassified was formally recognized as a class, conjecturally referred to on the Wiki as Specialist. This class absorbed many of the former Disruptors.
While not yet active within the client or on the website, Riot employees and shoutcasters now actively use the new class system.
- Three champions currently contain a Class within their title: , and . Incidentally, not one of these champions is in their implied class.
- The given Class only represents the role that a champion was explicitly designed to fulfil, and their recommended items will be geared toward fulfilling the role. However, players are free to explore whatever variation they desire - such as Artillery Kog'Maw.
- Before the classes and subclasses changes, there were very few champions with just single class and most of those were either mages or marksmen. As of May 24th, 2017, only 4 champions feature secondary classes.
- There has never been a Melee Marksman.
- There has never been a champion classified as both Assassin and Tank.
- Mages. During the development of the class rework, was briefly classified as a Burst champion. and are the only physical-damage champions to have ever been classified as
- Prior to the class rework:
- was once classified as an assassin and controller.
- was once classified as a fighter and controller.
- was once classified as a marksman and tank.
- was once classified as a marksman and controller.
- Controller as their only class. Before him, all other "supports" had a secondary class. was the first champion released with