Lucky the Rancor is the Worldboss of Corellia in SWTOR, he can be found in his enclosure at the Coronet Zoo, which is the exact center of the Axial Park District map on the planet.

Lucky was once a regular brown Rancor until Rise of the Hutt Cartel introduced the Dread Seed corruption to various planets in the game, which corrupted both Lucky and his enclosure. You are able to earn both of the Worldboss’ titles on the same character as Lucky has a roughly 15 minute respawn (may be faster if the Feast of Prosperity Event is running). Keep in mind both titles are “Character Bound” meaning that to unlock the titles on your alts you must re-do the Boss on those characters.

To earn the Title: “Unlucky <Charactername>”, you simply have to jump into the enclosure and have Lucky kill you, making it the easiest and most common to earn as a reward.
To earn the Title “Lucky <Charactername>”, you have to defeat Lucky once, or be in a group of players that defeat Lucky even if you died before the boss was defeated.
Lucky is a fairly easy Worldboss to kill, he doesn’t have many attacks, but has a very high amount of health. This means that the smaller group you’re in, the longer it can take (upwards of 15-20 minutes in a group of 4, 4-5 minutes in a group of 20).

You are able to earn both the Unlucky and Lucky Title at the same time, as long as you die at the beginning to Lucky, then respawn and attack the boss at least once before it dies. Just make sure that you take a combat/field revive and do not choose to respawn at the closest Med Center as it can be a lengthy walk back, and the boss may die before you return.