Catherine Jane Bonar (née Lundie), frequently recorded in hymnals as Mrs. Catherine J. Bonar or Mrs. Horatius Bonar, was a 19th-century Scottish hymnwriter and poet. Born at the Kelso Manse in Kelso, Roxburghshire, in December 1821, she was the daughter of the Reverend Robert Lundie, minister of Kelso parish. Raised in a devout and literary household, she developed a deep love for sacred verse early in life. In 1843, she married the celebrated Scottish minister and hymnwriter Horatius Bonar, partnering with him in pastoral and literary labors throughout his ministry in Kelso and Edinburgh.

Her original hymns were contributed anonymously or under initials to collections compiled by her husband, including Songs for the Wilderness (1843–1844) and The Bible Hymn Book (1845). Her writing is marked by deep personal devotion, spiritual simplicity, and an intense focus on total consecration to Jesus Christ.

Her most famous and enduring contribution to international hymnody is the beloved consecration hymn "Pass away, earthly joy" (written around 1843 and published in Songs for the Wilderness, 2nd Series, 1844). Set with the recurring refrain "Jesus is mine!", the hymn expresses the soul's contentment in Christ above all temporal wealth and earthly pleasure. In American and later international hymnals, the text was famously altered to begin "Fade, fade, each earthly joy," becoming a standard devotional text across Protestant denominations worldwide and translated into German, Portuguese, Norwegian, Dutch, Chinese, Tamil, and other languages.

Her notable hymnological contributions include:

• "Fade, fade, each earthly joy" (originally "Pass away, earthly joy") — A classic hymn of personal consecration and quiet trust in Christ.

• "Now I have found a Friend" — Her final stanza of "Pass away, earthly joy" was widely appended as the concluding stanza of Henry Hope's famous hymn.

Catherine Jane Bonar died in Edinburgh on December 3, 1884, at the age of sixty-three, leaving behind a brief yet globally cherished legacy of devotional song.