All conventional pens and pencils work in space.
The most commonly used item is probably a Sharpie felt-tip permanent marker because it can be used to write on almost any surface, including plastic bags and fabric. Mechanical pencils are probably the second most used - primarily for jotting down numbers in procedure pads. But even regular ballpoint biro pens are used on-orbit. For some reason some people think that because a ballpoint pen doesn’t work very well when upside down that it wouldn’t work in space. Um, it doesn’t work well upside down on Earth because gravity. In space the ink will not fall back away from the nib. Surface tension will keep the ink together and flowing.