Colin Moriarty

Colin Moriarty is Megaton's crime boss and the owner of Moriarty's Saloon, and speaks with a slight Irish accent. He has a computer which contains valuable information on the game's main quest. To access the information, you can either pay/speech Moriarty for it, get the info from Nova, the local prostitute working for Moriarty, or convince Gob, the ghoul bartender, to tell you how to access his boss' computer. The player can also go into sneak mode, pickpocket Moriarty's key from him, use it to open a cabinet in the back that contains his computer's password and gain the information that way. If you pay Jericho 20 caps for information, he will tell you that Moriarty keeps the payroll for Nova and Gob locked by his bed. Moriarty's bed is located upstairs in his saloon. Jericho informs you that Moriarty keeps the key around his neck.

If you are planning on blowing up Megaton and thus are not worried about bad Karma and can catch Moriarty in the back room at his computer, you can close the door and kill him (after taking to him about your father) and loot him and everything back there.

Unfortunately, in the unpatched release version of Fallout 3, this key appears to be missing for some users playing the PC version of the game and cannot be pick-pocketed, However some other PC users have no such bug.

Moriarty seams to be the only Irishman in the game

Appearances
Moriarty appears only in Fallout 3.

Behind the scenes
Colin Moriarty is also a writer for the gaming news site, IGN.com and in one of his own Podcasts (Three Red Lights Ep. 44a) he says the character in Fallout 3 is named after him due to his status in the gaming community. He is a writer of many gaming FAQ's for the website. He has said that writing the FAQ for Fallout 3 will be very difficult for him. For more information on IGN's Colin Moriarty, see http://faqs.ign.com/articles/378/378384p1.html. Moriaty being the town crime boss may also reference the famous enemy of Sherlock Holmes, professor Moriaty.

Known Bugs and Solutions
Moriarty has been reported to disappear into the wasteland making it difficult to complete the main quest. To determine if this has happened, select a quest involving Moriarty as the target (generally Following in His Footsteps), then bring up the World Map. If the marker for Moriarty appears north-east of Springvale School, then you can safely assume he has wandered away. This can be a dealbreaker for players who wish to do play with Good Karma, as the alternate solutions involve talking the information out of Gob or Nova and potentially hacking Moriarty's computer, though the small amount of negative Karma can easily be countered by simple tasks like giving scrap metal to Walter, giving water to Micky, or donating money to the Children of the Atom. Alternatively a player can simply wait and finish Following in His Footsteps by visiting Rivet City during the The Wasteland Survival Guide quest and speaking with Doctor Li. This results in no karma loss and the added benefit of discovering Rivet City relatively early in the game.

While playing PC version you can also bring him back by following Recovering missing NPC in Fallout 3 guide.

Using the Mesmetron on him will have the same effect on all non aggressive npcs. However even though he dies, the other npcs in the town will all act as if he is alive and you will still get the objective to talk to him about Dad.

It is possible to kill Colin (when he's out taking a smoke in front of the bar is probably the best time if you want to avoid the angry mob that forms afterward) and for things to change slightly in Megaton after. Killing him results in Bad Karma, even though nothing bad seems to happen because of his death. In fact, Nova will stop selling herself and take over running the saloon, charging the same rate for rooms - without her companionship, of course. Gob will start greeting you by begging you not to shoot and end conversations begging not to be hit. Despite this, he will still sell items and sound quite friendly and agreeable when he does so ("Anything for you, friend.") if you were nice to him before. Manya also refers to Colin's death, saying that nobody's really in charge of the town anymore with Colin and Lucas Simms dead.