Yes, with a couple caveats.
No doubt about it, using the wrong type of spatula or spoon on certain kinds of pans will damage them (see our guide to which utensils are best with each type of cookware for a complete break-down), but when it comes to cast iron, it all depends on the age and condition of the skillet. Can you use metal spatulas on cast iron? Yes, but with a couple caveat.
Ideally, you should always season your cast iron before you use it, but if you’re using brand-new, unseasoned cast iron or a pan that you’ve only just seasoned, you should use gentle silicone or bamboo cooking utensils. After your skillet has been used a few times and the seasoning has gotten even better, it has a nonstick finish that’s much hardier than factory-produced nonstick, in that it can stand up to metal utensils without damage.
Know that seasoning cast iron is not a one-and-done deal; you’ll want to make sure to properly clean it to prolong the coating, which should only get better with each use (but will be ruined by improper care like letting water sit in the pan).
If you have enameled cast iron (think Le Creuset or other Dutch ovens), a metal spatula is not the best tool for the job, as it will leave marks. Enameled cast iron is still extremely strong, so these are likely not actually scratches, but streaks of metallic residue that can be cleaned up with Bon Ami, Bar Keeper’s Friend, or even denture tablets. Still, better to use silicone or wooden utensils with this type of cast iron, and save the metal spatulas for your properly seasoned (but otherwise naked) cast iron skillet.
You can also use metal utensils with your seasoned carbon steel pans.
Another tip: Choose metal utensils that are all one piece, without rubber handles and rivets that can melt or otherwise break down faster.