I generally don't do single page character sheets, but this assassin popped into my head fully formed.
The Swindle Pig is an atypical assassin. His real name is unknown, but he goes by “Patch”, “Plug” and “Paully”. Sometimes, in the same conversation.
He specializes in information gathering. He is able to provide the player characters with many useful details.
From the DM side, The Swindle Pig excels at spycraft so he knows what the party needs. He is horrible at negotiation, so he doesn’t bother. He offers his information for “free” at the outset and explains that people should repay him according to their means once the information proves useful.
This sort of indebted exchange rubs a lot of people wrong, but they still pay accordingly.
Many player characters will realize that The Swindle Pig is an excellent assassin and fighter but he sees no value in killing people if he doesn’t have to. On the other hand, people who try to cross him or the people he networks with will end up very dead. He will never double cross honest people and won’t work with honorless people.
The Swindle Pig has two journals or notebooks. He is very educated and has excellent penmanship. When he gives out information, he writes it on a page in the red book and tears it out. When someone gives him a reward, he places their names in the black book, no matter the amount.
There is a story about him rescuing someone who came to harm from his information. It’s an ugly tale, but also proof positive that he is honorable.