Especially noteworthy dwarves (particularly military dwarves with an impressive kill) get custom professions. Here's a list.
Aban Gearedwild ('The Granite World of Minds'): Titanslayer, awarded for defeating a titan. His custom profession has not changed despite downing a forgotten beast, a cyclops, and several goblins/trolls with not a single further wound on "skilled" or "proficient" military skills only -- because frankly "Titanslayer" is about as awesome as it gets.
(several dwarves): Beast Killer, awarded for downing a Forgotten Beast. This would probably be "upgraded" if any of them survived to earn another (semi)megabeast kill, but deadly dust and crippling wounds tend to end military careers. Of three Beast Killers, one expired in the hospital, another was perforated by marksgoblins while trying to kill an ambush, and the third, after being crippled but still active duty, died in the shiny new danger room, presumably due to a general inability to dodge the training spears -- I've checked, they are all home-made training spears.
Rakust Laboracted: Ettinbane, earned for killing an Ettin. Time will tell if Rakust earns anything better.
Tulon Rhymewheel ('The Spiral of Furnaces'): Vengeance-Taker, awarded for, in the early days of the fortress, beating the cave fish man that killed her lover into a bloody pulp for several pages of combat log with her cat-bone crossbow, before another dwarf finally stepped in and mercy-killed the thing. The coolness factor of her prior achievements is probably the only reason I don't let her have an accident over those aluminum mandates now that she's duchess. (I promoted her without checking her prefs because she had been mayor for a brief term, and mandated greaves before forbidding the export of bolts -- nice and easy. Plus, with a dead lover, I wouldn't have to worry about an unlisted noble-consort causing trouble)
Dwarves with (semi)megabeast kills are also awarded special tombs, with slabs recounting the beasts they've defeated. Everyone else who's not a lifetime noble just gets a coffin behind a door.
In future forts, I'll probably go farther with custom professions, or change the init options to put nicknames between first and last rather than overwriting the first name, so I can get more creative with nicknames -- 'goblin fodder' as a profession for (future) recruits, removed when they have the skill to be a {weapon}dwarf, for instance, or Urist 'Wrongway' McMason for the highly skilled fool who keeps locking himself on the wrong side of walls. (though I've MOSTLY cured that with the suspended wall trick)