As a counterpart to the girls going to bars thread, I’ll ask the same question to the guys out there.
I go to bars by myself all the time. Plenty of reasons:
I sit at the bar and read the newspaper in peace and quiet while enjoying a pint. I don’t do it often, but boy do I enjoy it when I get the opportunity.
Back in the day, I did it all the time. I would usually take something to read and sit at the bar. Sometimes someone would talk to me but usually I just kept to myself and I never hit on anyone. It was one of my favorite things to do and I never felt awkward at all.
Back in the days when I was single, I would prefer going to bars alone.
I could hang out with friends I met there if I wanted to, or I could leave and go somewhere else without having to wait for someone.
Also, going by yourself allows you to move away from one group and go talk to another group or single person without having to go into great explanation why and who for how long, etc.
Plus, part of the reason of going to a bar alone was so that I might not have to go home alone, if you get the drift.
It makes it a whole lot easier to quietly leave with someone if you don’t have to worry about how other people are going to get home, or if you need to get your jacket out of the car etc.
I have a handful of times (not counting when traveling). Of course, it helps when you’re friends with lots of bartenders. 
Usually with something to read. I’m bad at making conversation, so I pretty much just chill with myself until I get bored, or until someone nearby gets tipsy and talkative. Then again, I ended up making friends with this couple in Boston because they were having a deep conversation about Snakes on a Plane, and I couldn’t help but crack up.
Are there boobies involved?
If I am away from home alone sometimes I might drop into a bar to have a drink if I’m in the mood. Or to have a nosh. But I get bored quickly and since I don’t usually start talking to strangers and I am not in the market for female companionship I usually leave pretty soon. Doesn’t happen very often since I am mostly at home or work. Yes I’m old and boring.
I used to go to bars alone back in the day. Learned to dance at a bar. Met my wife at a bar. We’ll have been married 20 years in Sept.
At least once a week I go to my local, have a couple of pints, and read the latest Chicago Reader and Onion so I can plan out the weekend. I’ll usually take a book along to read if I finish the papers before I finish my dinner/beer. I’ll chat with the bartender if it’s not overly busy, or occasionally watch the TV if there’s something interesting on.
Same here, though I did start talking to some of the regulars as I got to know them. The pub I used to go to was about a mile away from my house, so having that pint at the end of the walk was really gratifying.
This one’s easy.
I go to play pool. (the bar I frequent is a pool hall)
Yeah I do it. I usually go, chill, get slightly to heavily drunk, and talk to strangers. Last year there was the thought of picking somebody up, but it never happened and I’m taken now. I especially go if there’s karaoke. Me loves teh karaoke.
I used to, but this place I’ve just moved to doesn’t really have any bars to my taste. When I did, it was generally because I was mixing two things I happen to greatly enjoy: booze and people watching. I’ve made my fair share of friends after going to a bar alone, but I’ve never tried to pick anyone up or anything like that. I usually went to the two or three bars where I knew the bartenders pretty well, too, so that helped.
Sometimes bars have pool/ping pong/darts. Sometimes you’re looking to meet women. Assuming neither of those cases, sometimes it’s nice to be somewhere just anonymously drinking and either relaxing and/or people watching. You sit down, get a nice cool pint on tap, and just hang out for a bit.
Now the bars that I are close to me I know the bartenders, so I go hang out and talk to them. I’ve also taken to studying there-- I’ll just bring my course materials and read and sometimes drink alcohol and sometimes not.
I used to go to bars alone often. Usually it was to see a particular band play. Gettin’ old, get sleepy too early.
I go to bars (nightclubs) alone if it is a major event advertised, long lines, crowds. Because then I will usually bump into someone I know. Plus the music is better when they draw in a big crowd.
I go to a casual or eclectic bars with a group of friends occasionally.
I don’t do it very often, but when I do, I just get a drink and read a book/newspaper/magazine…
Yes, in about 5 hours from now. I nearly always go alone but since I’ve been using this pub for 10 years I’m guaranteed to find someone I know.
I used to when I was working on a show building sets. It was always so rushed and so high stress, that I’d go to pub and read a newspaper. By the end of the day, I really enjoyed the alone time. It was just right to calm down and decompress so I could be human again by the time I got home. It became a regular thing: pint and newspaper.
I think the last time I went to a bar by myself in any kind of regular way was one year during March Madness so I could watch the games.
The bars I go to have live music. I go to drink, listen to music, and sometimes enjoy some female companionship. Not so much recently, as this was how I met my gf a few years ago.
I occasionally visit a quiet pub and sit there with a pint and a book.