There is a broad spectrum of needy, so first you’ll need to determine where this person falls on the um, spectrum.
Depending on the degree of need, your reaction could range from getting their stomach pumped to ignoring them completely. Some things can be your responsibility just by being a human in the same room, but most things are not.
The other consideration is the placement of their need. If you find yourself exasperated by all their questions and requests for time off, you may be alarmed to learn that you are, in fact, their manager and no one told you.
In that case, their need for answers about their duties is placed with you, as it should be. Be a kind manager and leave a door open for them. (Or the porthole, if applicable).
If they have a need for sexy banter and you are not a sexy banter operator, that would be improper placement of their need. See? It’s fine for them to need that, but they do not need that from you at work unless it’s your job.
If they need to watch videos of livestock reacting to the latest torch ballad at your work station and you are not an incognito media personality who is secretly recording them for public ridicule, well then, you know what I’m saying here. I hope.
Now for the hard part. I know you are a thoughtful coworker. You don’t burn fish in the microwave or eat loud snacks in your central cubicle, unless you are drunk. People appreciate that about you.
Some people, however, will see your thoughtfulness as softness and will try to press you into uncomfortable corners. That’s why it’s a very important work skill to say, “Nope.”
Embrace the Nope.
Practice with me. Let’s do some dialogue with your coworker. Let’s call him Steve.
Steve: Hey, can I crouch near your chair and whimper to you about my childhood for the next 45 minutes?
Steve: Hey, you look great. Can I borrow your underwear?
Steve: I have no idea what to do with this project and I’m afraid of our manager. Also, I’m afraid of frogs. Will you help me? With both things?
You: Double Nope.
Setting firm limits with people at work can be the thing that saves your job, not to mention your sanity. Just be wary of letting anyone make something your problem that is really not your problem. Gently point them to the proper resource and sometimes, pump their stomach.