Creating threat actor and campaign profiles
Usually, Threat Intelligence Platforms (TIPs) have a section with the profiles of different threat actors, their characteristics, the campaigns attributed to them, and their main TTPs.
If you do not have access to a TIP, you can still consult the information about threat actor profiles and their malicious campaigns from public sources such as MITRE ATT&CK (https://attack.mitre.org/groups/), AT&T OTX (https://otx.alienvault.com/browse/global/adversaries), or this compilation created by industry colleagues: https://apt.threattracking.com.
However, these information sources cover only threat actors with a specific visibility level due to the nature of their attacks or the relevance of their targets. So, there will be many others that do not appear there, but they threaten organizations nonetheless.
Sometimes, organizations should create their own internal threat actor profiles and campaigns from their incident response...