Depends on your 'reef', a lot of fish considered not reef safe are perfectly fine in certain situations. Some large angels and butterflies, for instance, will devour LPS corals but leave SPS and soft corals alone for the most part.
Angels:
Genicanthus genus is reef safe.
Centropyge genus is *usually* reef safe, depends on the species and the corals. IME C. argi is the most reefsafe.
Pomacanthus genus has some species that are Ok with SPS and clams, sometimes. P. navarchus and P. imperator are the ones I see most often in reefs.
Anthias are always reefsafe
Assessors are a little group I'm in love with that are perfectly reefsafe.
Basslets are almost always reefsafe...some might eat small shrimp.
Blennies are usually ok, but they can sometimes nibble on clams. There's one species that feeds exclusively on Acropora polyps.
Butterflies are a mixed bag. Heniochus genus has some reefsafe species, as does Forcipger genus.
There are others that are borderline in the Chaetodon genus, like C. tinkeri. Others are outright coral predators.
Clowns are all reefsafe.
Damsels and Chromis are all Ok, but can become nasty aggressive little fish. All the chromis and the damsel Chrysiptera parasema are fairly peaceful though.
Dottybacks can mess with small shrimp, and are usually very aggressive. There are some exceptions...P. fridmani is very peaceful.
Gobies are almost all Ok, it's such a big group there are probably exceptions somewhere. Stonogobiops genus and some other genera associate with Alpheus pistol shrimps, which is kind of a cool symbiotic relationship to watch.
Grammas are all reefsafe. They might bother small shrimp added after them.
Firefish are always reefsafe and very peaceful, except to congeners.
Jawfish are reefsafe, although big ones might go after small shrimp.
Mandarins are reefsafe, but you wouldn't want to keep one with an anemone.
Seahorses/pipefish are reefsafe, but do better in low flow species tanks.
Tangs are all reefsafe. Sometimes they nibble at clams if they're very hungry, but usually do no damage.
Triggers are pretty much not reef safe, but the plankton feeding genera are Ok with corals...Odonus niger and Xantho...man I forget the spelling, but the blue jaw and pinktail triggers are Ok in reefs. They get very big though.
Wrasses:
Cirrhilabrus, Wetmorella, and
Paracheilinius genera are all reefsafe.
Bodianus,
Pseudocheilinius,
and Halichoeres genera are usually fine, but can sometimes attack small shrimp.
...there are others that probably won't bother corals but will hunt down fish, shrimp, snails, etc.
There are always exceptions in every group too...there are NON reef safe blennies and reef safe triggers. And of course most big predators are coral safe but limit your other fish/invert options.
An incomplete list, but I hope this helps!
Matt