The Xeon Phi was a “manycore” x86 design with lots of tiny CPU cores, something like the original Pentium, but with the addition of 512-bit SIMD and hyperthreading:
The very, very first Phi still had its ROPs and texture units, being essentially a failed GPU with identifying marks filed off (yes, the first units were Larrabee prototypes with video outputs unpopulated)
GPUs are actually SMT'd to the extreme. For example, Intel's Xe-HPG has 8-wide SMT. Other vendors have even bigger SMT: RDNA2 can have up to 16 threads in flight per core.
https://en.m.wikipedia.org/wiki/Xeon_Phi