Over the past 30 years, most companies have added new C-level roles in response to changing business environments. The chief financial officer role, which didn't exist at a majority of companies in the mid-1980s, rose to prominence as pressures for value management and more transparent investor relations gained traction. Adding a chief marketing officer became crucial as new channels and media raised the complexity of brand building and customer engagement. Chief strategy officers joined top teams to help companies address increasingly complex and fast-changing global markets. Today, the power of data and analytics is profoundly altering the business landscape, and once again companies may need more top-management muscle.