NEC produced unlicensed 80(1)86/8 with different microcode (also Z80 compatible), that were faster than intels. Intel sued and lost.
IBM, Cyrix, C&T, TI had 3/486 with different microcode. Some had compatibility problems in executing x86 code.
AMD first used 3/486 intel microcode, but, due to legal problems with intel, used later their own microcode.
UMC produced a 486 unlicensed clone... just it couldn't sell them in patentland.
Pentium compatibles were AMD K5/6(-2,III), Cyrix 6x86(L,MX,MII), IDT(Centaur) C6(+) for Socket5/7.
NexGen 686 had a similar design (later included in AMD K6), but for proprietary socket.
After that, intel and AMD have gone their own ways: Socket8, Slot1/2, Socket370, 423, 478, 479, 603, 771, 775, 1366 ... respectively SlotA, SocketA, 754, 939, 940, 1207... and their own bus signaling.
VIA aquired Cyrix and Centaur, and produced Socket370 compatible CPUs until 2006, when the license expired, and Socket479 ones, but with different signaling, for legal issues.