Intel Celeron 266
A boxed version of the first Celeron series. Basically the Celeron Covington is a Pentium II without L2-cache. This reduces production costs but also causes performance to drop. No L2-cache at all is not good. It's successor, the Celeron Mendocino, had 128K2 full-speed on-die cache which greatly improved the CPU.
I like the box-art of the Celeron 266. A blue little box showing the hardware that is underneath the black plastic shroud.