The WellTempered Clavier, BWV 846–893, is two sets of preludes and fugues in all 24 major and minor keys for keyboard by Johann Sebastian Bach. In the composer's time clavier, meaning keyboard, referred to a variety of instruments, most typically the harpsichord or clavichord but not excluding the organ.

The modern German spelling for the collection is Das wohltemperierte Klavier (WTK; German pronunciation: [das ˌvoːlˌtɛmpəˈʁiːɐ̯tə klaˈviːɐ̯]). Bach gave the title Das Wohltemperirte Clavier to a book of preludes and fugues in all 24 keys, major and minor, dated 1722, composed "for the profit and use of musical youth desirous of learning, and especially for the pastime of those already skilled in this study". Some 20 years later Bach compiled a second book of the same kind, which became known as The WellTempered Clavier, Part Two (in German: Zweyter Theil, modern spelling: Zweiter Teil).

Modern editions usually refer to both parts as The WellTempered Clavier, Book I (WTC I) and The WellTempered Clavier, Book II (WTC II), respectively. The collection is generally regarded as one of the most important works in the history of classical music.

J.S. Bach The WellTempered Clavier, Book 1: Preludes and Fugues (performed by Sviatoslav Richter):
0:00 – Prelude No. 1 in C major
1:56 – Fugue No. 1 in C major
4:29 – Prelude No. 2 in C minor
5:47 – Fugue No. 2 in C minor
7:28 – Prelude No. 3 in Csharp major
8:43 – Fugue No. 3 in Csharp major
10:50 – Prelude No. 4 in Csharp minor
14:03 – Fugue No. 4 in Csharp minor
20:26 – Prelude No. 5 in D major
21:35 – Fugue No. 5 in D major
23:30 – Prelude No. 6 in D minor
24:56 – Fugue No. 6 in D minor
27:32 – Prelude No. 7 in Eflat major
31:13 – Fugue No. 7 in Eflat major
32:43 – Prelude No. 8 in Eflat minor
37:08 – Fugue No. 8 in Eflat minor
43:35 – Prelude No. 9 in E major
44:40 – Fugue No. 9 in E major
45:48 – Prelude No. 10 in E minor
47:41 – Fugue No. 10 in E minor
48:50 – Prelude No. 11 in F major
49:45 – Fugue No. 11 in F major
51:04 – Prelude No. 12 in F minor
53:14 – Fugue No. 12 in F minor
58:39 – Prelude No. 13 in Fsharp major
1:00:03 – Fugue No. 13 in Fsharp major
1:02:21 – Prelude No. 14 in Fsharp minor
1:03:11 – Fugue No. 14 in Fsharp minor
1:07:30 – Prelude No. 15 in G major
1:08:18 – Fugue No. 15 in G major
1:10:44 – Prelude No. 16 in G minor
1:12:42 – Fugue No. 16 in G minor
1:15:35 – Prelude No. 17 in Aflat major
1:16:46 – Fugue No. 17 in Aflat major
1:19:43 – Prelude No. 18 in Gsharp minor
1:21:07 – Fugue No. 18 in Gsharp minor
1:24:35 – Prelude No. 19 in A major
1:25:46 – Fugue No. 19 in A major
1:28:25 – Prelude No. 20 in A minor
1:29:20 – Fugue No. 20 in A minor
1:33:30 – Prelude No. 21 in Bflat major
1:34:36 – Fugue No. 21 in Bflat major
1:36:08 – Prelude No. 22 in Bflat minor
1:38:34 – Fugue No. 22 in Bflat minor
1:42:56 – Prelude No. 23 in B major
1:43:48 – Fugue No. 23 in B major
1:46:23 – Prelude No. 24 in B minor
1:54:14 – Fugue No. 24 in B minor