Compatible with the original Z80
Hitachi developed the HD64180, a microcoded and partially dynamic Z80 in CMOS, with on chip peripherals and a simple MMU giving a 1 MB address space.
It was later second sourced by Zilog, initially as the Z64180, and then in the form of the slightly modified Z180 which has bus protocol and timings better adapted to Z80 peripheral chips.
Z180 has been maintained and further developed under Zilog's name, the newest versions being based on the fully static S180/L180 core with very low power draw and EMI (noise).

Toshiba developed the 84 pin Z84013 / Z84C13 and the 100 pin Z84015 / Z84C15 series of "intelligent peripheral controllers", basically ordinary NMOS and CMOS Z80 cores with Z80 peripherals, watch dog timer, power on reset, and wait state generator on the same chip.
Manufactured by Sharp as well as Toshiba.
These products are today second sourced by Zilog.

The 32-bit Z80 compatible Zilog Z380, introduced 1994, is used mainly in telecom equipment.

Zilog's fully pipelined Z80 compatible eZ80 with an 8/16/24-bit word length and a linear 16 MB address space was introduced in 2001.
It exists in versions with on chip SRAM or flash memory, as well as with integrated peripherals.
One variant has on chip MAC (media access controller), and available software include a TCP/IP stack.
In contrast with the Z800 and Z280, there are only a few added instructions (primarily LEAs, PEAs, and variable-address 16/24-bit loads), but instructions are instead executed between 2 and 11 times as clock cycle efficient as on the original Z80 (with a mean value around 3-5 times).
It is currently specified for clock frequencies up to 50 MHz.

Kawasaki developed the binary compatible KL5C8400 which is approximately 1.2-1.3 times as clock cycle efficient as the original Z80 and can be clocked at up to 33 MHz.
Kawasaki also produces the KL5C80A1x family, which has peripherals as well as a small RAM on chip; it is approximately as clock cycle efficient as the eZ80 and can be clocked at up to 10 MHz (2006).

The NEC µPD9002 was a hybrid CPU compatible with both Z80 and x86 families.

The Chinese Actions Semiconductor's audio processor family of chips (ATJ2085 and others) contains a Z80-compatible MCUs together with a 24-bit dedicated DSP processor.
These chips are used in many MP3 and media player products.

The T80 (VHDL) and TV80 (Verilog) synthesizable soft cores are available from OpenCores.org.

Non-compatible
The Toshiba TLCS 900 series of high volume (mostly OTP) microcontrollers are based on the Z80; they share the same basic BC,DE,HL,IX,IY register structure, and largely the same instructions, but are not binary compatible, while the previous TLCS 90 is Z80-compatible.

The NEC 78K series microcontrollers are based on the Z80; they share the same basic BC,DE,HL register structure, and has similar (but differently named) instructions; not binary compatible.

Partly compatible
Rabbit Semiconductor's Rabbit 2000/3000/4000 microprocessors/microcontrollers are based on the HD64180/Z180 architecture, although they are not fully binary compatible.

No longer produced
The ASCII Corporation R800 was a fast 16-bit processor used in MSX TurboR computers; it was software, but not hardware compatible with the Z80 (signal timing, pinout & function of pins differ from the Z80).

Zilog's NMOS Z800 and CMOS Z280 were 16-bit Z80-implementations (before the HD64180 / Z180) with a 16 MB paged MMU address space; they added many orthogonalizations and addressing modes to the Z80 instruction set.
Minicomputer features — such as user and system modes, multiprocessor support, on chip MMU, on chip instruction and data cache and so on — were seen rather as more complexity than as functionality and support for the (usually electronics-oriented) embedded systems designer, it also made it very hard to predict instruction execution times.

Certain arcade games such as Pang/Buster Bros use an encrypted "Kabuki" Z80 CPU manufactured by VLSI Technology, where the decryption keys are stored in its internal battery-backed memory, to avoid piracy and illeg
Compatible with the original Z80
Hitachi developed the HD64180, a microcoded and partially dynamic Z80 in CMOS, with on chip peripherals and a simple MMU giving a 1 MB address space. It was later second sourced by Zilog, initially as the Z64180, and then in the form of the slightly modified Z180 which has bus protocol and timings better adapted to Z80 peripheral chips. Z180 has been maintained and further developed under Zilog's name, the newest versions being based on the fully static S180/L180 core with very low power draw and EMI (noise).
Toshiba developed the 84 pin Z84013 / Z84C13 and the 100 pin Z84015 / Z84C15 series of "intelligent peripheral controllers", basically ordinary NMOS and CMOS Z80 cores with Z80 peripherals, watch dog timer, power on reset, and wait state generator on the same chip. Manufactured by Sharp as well as Toshiba. These products are today second sourced by Zilog.
The 32-bit Z80 compatible Zilog Z380, introduced 1994, is used mainly in telecom equipment.
Zilog's fully pipelined Z80 compatible eZ80 with an 8/16/24-bit word length and a linear 16 MB address space was introduced in 2001. It exists in versions with on chip SRAM or flash memory, as well as with integrated peripherals. One variant has on chip MAC (media access controller), and available software include a TCP/IP stack. In contrast with the Z800 and Z280, there are only a few added instructions (primarily LEAs, PEAs, and variable-address 16/24-bit loads), but instructions are instead executed between 2 and 11 times as clock cycle efficient as on the original Z80 (with a mean value around 3-5 times). It is currently specified for clock frequencies up to 50 MHz.
Kawasaki developed the binary compatible KL5C8400 which is approximately 1.2-1.3 times as clock cycle efficient as the original Z80 and can be clocked at up to 33 MHz. Kawasaki also produces the KL5C80A1x family, which has peripherals as well as a small RAM on chip; it is approximately as clock cycle efficient as the eZ80 and can be clocked at up to 10 MHz (2006).
The NEC µPD9002 was a hybrid CPU compatible with both Z80 and x86 families.
The Chinese Actions Semiconductor's audio processor family of chips (ATJ2085 and others) contains a Z80-compatible MCUs together with a 24-bit dedicated DSP processor. These chips are used in many MP3 and media player products.
The T80 (VHDL) and TV80 (Verilog) synthesizable soft cores are available from OpenCores.org.
Non-compatible
The Toshiba TLCS 900 series of high volume (mostly OTP) microcontrollers are based on the Z80; they share the same basic BC,DE,HL,IX,IY register structure, and largely the same instructions, but are not binary compatible, while the previous TLCS 90 is Z80-compatible.
The NEC 78K series microcontrollers are based on the Z80; they share the same basic BC,DE,HL register structure, and has similar (but differently named) instructions; not binary compatible.
Partly compatible
Rabbit Semiconductor's Rabbit 2000/3000/4000 microprocessors/microcontrollers are based on the HD64180/Z180 architecture, although they are not fully binary compatible.
No longer produced
The ASCII Corporation R800 was a fast 16-bit processor used in MSX TurboR computers; it was software, but not hardware compatible with the Z80 (signal timing, pinout & function of pins differ from the Z80).
Zilog's NMOS Z800 and CMOS Z280 were 16-bit Z80-implementations (before the HD64180 / Z180) with a 16 MB paged MMU address space; they added many orthogonalizations and addressing modes to the Z80 instruction set. Minicomputer features — such as user and system modes, multiprocessor support, on chip MMU, on chip instruction and data cache and so on — were seen rather as more complexity than as functionality and support for the (usually electronics-oriented) embedded systems designer, it also made it very hard to predict instruction execution times.
Certain arcade games such as Pang/Buster Bros use an encrypted "Kabuki" Z80 CPU manufactured by VLSI Technology, where the decryption keys are stored in its internal battery-backed memory, to avoid piracy and illeg
Zilog Z80