Is MR16 always 12V?

The answer to this question is not a straightforward "yes" or "no." While the MR16 bulb is commonly associated with being a 12V bulb, there are actually a few other voltage options available for this type of bulb.
In addition to the standard 12V MR16, there are also 24V MR16 bulbs available. These bulbs are often used in commercial or industrial applications where a higher voltage may be required. The higher voltage allows for longer runs of bulbs without as much voltage drop.
Another option for MR16 bulbs is the low voltage MR16, which typically runs on 6V. These bulbs are not as commonly used, but they can be handy in certain situations where a lower voltage is required.
So, while the MR16 bulb is often thought of as being a 12V bulb, there are certainly other voltage options available. It all comes down to your specific needs and the requirements of your lighting application. When looking for MR16 bulbs, be sure to double-check the voltage to ensure that you are getting the right bulb for your needs.