Players have generated many builds over the years. They have been collected in Compendiums for ease of viewing.
Additionally people have created various build collections. Or you can search for builds with the below Class Table, which organizes threads by class tags.
The top diagonal lists the nine basic masteries. At the intersection of two masteries you find the corresponding dual-class name, which links you to builds and discussions related to it. The masteries themselves are linked to rare single mastery builds, but not all builds which include that mastery.
FAQ
The above links partly overlap with the Build Compendiums. Visit them for more detailed build descriptions. Depending on if you only have the base game or also the expansion(s), not all builds are relevant to you. Not only do Inquisitor and Necromancer require the Ashes of Malmouth expansion and Oathkeeper Forgotten Gods, but the expansions have also added new items and constellations. Even if a build does not use the new masteries, it might rely on other stuff, which would not be available to you unless you acquire the necessary expansion(s).
You can refer to the game version, which is often used in the title:
As thread owner you can add up to five tags to your initial post. In addition to the class you can specify damage types, play-style, sets, Monster Infrequents, signature skills and other descriptors. Mythical and Empowered sets and items share their tag with lower level versions. Click my avatar to message me, if you miss a tag and cannot create it yourself.
The number behind each link is a click counter. Due to a change of the forum software I updated the links in the table on Sep 23rd 2021, which reset all counters. Until then the most popular dual-classes were Warlord, Death Knight, Purifier and Cabalist with over 10K clicks each and the least popular ones were Apostate, Saboteur, Deceiver and Defiler with less than 3K clicks each (decending order for both).
For seeing the number of topics go to the list of tags. As of Sep 24th 2021 tags are grouped, which has immensely improved readability.
#52d6b1 #dc7935 orchid slategray slateblue #80d64d #ff3030 #0099ff #dfaa4c
Colors of the original six masteries provided by Xeilua.