/u/Frostywookiee has cleverly sorted out the archetypes of Destiny raiders and Trials players. However, he has neglected the real endgame for Destiny: /r/DestinyTheGame. This list is far from everybody you will encounter, but it does cover the most common archetypes of folks you will encounter on this sub.
1) The Downvoter: This guardian immediately downvotes all new posts. His philosophy is survival of the fittest. If your montage, lore item, news or shitpost survives the immediate flurry of downvotes, then it could be good enough for the front page. If you never read this post, it will be due to the eternal vigilance of the Downvoter.
2) The Cynic: The Cynic is the salt of the sub. He/she deeply cares about Destiny, and is genuinely concerned with its long-term viability, but the Cynic wants to make sure that everyone on the sub is well aware of the game's flaws. For the Cynic, perfection is achievable and failure to reach perfection is due solely to a lack of effort and poor decision-making.
3) The Optimist: Often locked in conflict with the Cynic, the Optimist would rather dwell on Destiny's achievements rather than its failures. Although no less frustrated when things go haywire, the Optimist is frequently seen trying to decrease salt levels in times of crisis.
4) The Montager: The Montager spends much of his/her time playing Destiny seeking those rare moments of excellence to combine into a 1:30 minute video of pure glory. Frequently, the Montager masquerades as "a friend" of the player, stating that the friend is too embarrassed to let his talent shine. Montagers frequently pull double duty as Downvoters to give their montage a better chance to make the front page.
5) The Leaker: The Leaker shows up from time to time with tidbits of information that are frequently invaluable, but are just as often false. Some Leakers become legend, like /u/megamanexe4 sama, others live only to pass on one piece of information, then fade into the mists of speculation.
6) The Content Generator: The Content Generator spends a great deal of time putting together Destiny-related content, which is frequently amazing in quality. Whether it be animation, drawings, review videos (satirical and real), or amazing feat videos (solo raids, etc.) the Content Generator's talents are frequently rewarded with large amounts of upvotes, and rightly so.
7) The Mods: The mods are the clergy of this sub. They create and enforce the catechism (the sacred Tower Rules), as well as the holy inside jokes (happy birthday /u/knowwhoyouare). They have the power to excommunicate, although they typically use their powers to purge posts and comments that violate the catechism.
8) The Sherpa: The Sherpa is the hero of the sub. Just as the raid sherpa guides the fireteam through each activity, the DTG Sherpas take an enormous amount of time sorting out and summarizing all of the information in Destiny. Whether it is keeping track of the time to kill for each weapon, informing which vendor rolls are 100% this week, posting the best strategy to defeat every PvE activity, or creating massive guides for everything, the Sherpas are the reason this sub is the unofficial strategy guide for Destiny.
9) The Information Seeker: The Information Seeker is often overlooked by the DTG community. The Information Seeker's posts rarely make it to the front page, as helpful guardians answer the Information Seeker's questions without much ado. Sometimes though, the Information Seeker's innocent question (for example regarding the remains in a cave in Skywatch) will trigger a wave of nostalgia among the community, boosting the Information Seeker's post to the front page.
10) The Clever Shitposter: The Clever Shitposter aims not to inform, but to delight. The Clever Shitposter is the lifeblood of a post's comments, and his/her posts are frequently the top comment. His/her comments may turn a relatively straightforward post from an Information Seeker (for example, with respect to a certain vendor roll) into a front page classic.
Think I missed any? Let me know in the comments.