This is likely the most famous release gap in modern popular music. Yusuf Islam was once Cat Stevens, purveyor of lithe folk-pop, until a near-drowning spurred him to vigorously investigate spirituality. He converted to Islam in 1977, and while he was prepared to forsake the pop-star life entirely, he owed his record company one final album. Recorded quickly, and released with no promotion from Yusuf Islam (still credited as Cat Stevens on the album), Back To Earth fared poorly in the marketplace. But Yusuf threw himself into benevolence, using his substantial royalties to fund schools and charities the world over. Though an imam had once granted him license to record pop music, he did not wish to work with an industry he considered inherently compromised. In the ’90s and ’00s, though, he released a series of devotional albums and compilations featuring himself and others on his own label. Already pondering whether he had withdrawn from mainstream culture too hastily, Yusuf was jolted by the World Trade Center attacks of September 11, 2001. He performed “Peace Train” a cappella for the Concert For New York City; over the next few years, he began performing more Cat Stevens compositions, culminating in the release of An Other Cup, his first pop release in 28 years. Splitting the difference, the record was credited both to Yusuf and Cat Stevens. Two more records followed, the second of which (Tell ‘Em I’m Gone) was released after Yusuf’s induction into the Rock And Roll Hall Of Fame in 2014.