When I'm manic, I'll have increased energy and increased creativity, be more exuberant and outgoing, and I'll sleep less ... but I'll also be more irritable and get angry easily. Sometimes I'm so angry I'll start experiencing homicidal ideation and think of killing other people. These people are usually the ones I'm the most angry at, and I know these thoughts are unrealistic and wrong, but I just can't get rid of them. I've even come up with entire plans, but never went through with any of them.
When I'm not manic, though, I don't have them.
I read once that homicidal ideation can occur in the manic and mixed episodes of bipolar disorder. But I have no idea how common it actually is.