IBM eServer was a family of computer servers from IBM Corporation. Announced in the year 2000, it combined the various IBM server brands (AS/400, Netfinity, RS/6000, S/390) under one brand. The various sub-brands were at the same time rebranded from:

• IBM AS/400 to IBM eServer iSeries, i for Integrated.
• IBM RS/6000 to IBM eServer pSeries, p for POWER
• IBM Netfinity to IBM eServer xSeries, x for eXtended architecture (with respect to "commodity" Intel-based servers)
• IBM S/390 to IBM eServer zSeries, z for Zero downtime