A lot of these aren't technically dead-names. They're parent corporations that exist to shuffle around profits and minimize tax and regulatory liabilities. Facebook and Google both continue to exist as properties owned by Meta and Alphabet.
That one has quite a few more steps, AT&T had to re-acquire Southern Bell>Bellsouth, Southwestern Bell, MCI, and a bunch of other subordinate companies to resurrect the reality of Ma’Bell
Gotta hate Time-Warner.
AOL-Time-Warner.