How many of the dead Blue Dragons did we have a hand in killing?

We're credited with killing Malygos on his tombstone, but there's a lot of other blue dragons who we had a hand in killing that don't mention us.

While we didn't kill them initially, Sindragosa, Sapphirion, and Eldragosa (Shivermaw) all went on to become Frost Wyrms, who we killed in Icecrown Citadel, Naxx, and Legion's Violet Hold respectively. This is also true of Arcanagos, who became Nightbane in Karazhan, and Madrigosa, who became Felmyst in Sunwell Plateau.

Saragosa mentions an unknown adventurer, (us) and we killed her on behalf of Keristrasza as part of a questline in Borean Tundra. We'd go on to kill Keristraza as a boss in Nexus after Malygos kidnaps and torturers her into insanity.

Also if you've ever completed Azure Vaults, you killed Umbrelskul, not sure why that one says Unknown.

Finally, you meet Arygos in AQ40, but I'm pretty sure his attempts to betray us all to Deathwing, and subsequent death, was only depicted in a comic. There's also a bit of lore about Balacgos out there, I believe from that same comic.

As far as I know, none of the rest existed as named characters before this patch, though apparently Stelagos died during that withered Nightfallen incursion on Azurewing Repose we helped fight back in Legion.