Intent is not needed
The definition of murder and manslaughter is actually quite short, NSW Crimes Act s18:
18 MURDER AND MANSLAUGHTER DEFINED
(a) Murder shall be taken to have been committed where the act of the accused, or thing by him or her omitted to be done, causing the death charged, was done or omitted with reckless indifference to ...
It depends on the jurisdiction, but in the U.S. first degree murder will always require premeditation. The time required can be quite short too... down to nearly instantly in some jurisdictions.
Second degree Murder will typically cover Murder that is "a crime of passion" (i.e. you come home to find you spouse in bed with another man/woman and fly ...