Can I change my last name at marriage to a name not used by myself or my spouse?
My Dad’s true name is Kaiser David Ansgar. When he immigrated to the US, in the immigration process he lost his last name (Ansgar). His middle name became his last name. So my last name is David, not Ansgar.
I’m a guy, and I’m going to get married soon and I wanted to know if I could use my current last name (David) as my middle name, and change my last name (David) to be my true last name (Ansgar)?
I wanted to know if I could do this on the marriage license or if I have to actually go through a legal name-change process requiring me to fill out a bunch of forms.

You will have to go through a name change and get a judge to approve the change.After a wedding ceremony you can change your name to your wife’s name or she can take your or you can combine the two.That’s it.Sorry.
Yes, you can. You’ll still need to file name-change papers, though.
yes, and in fact, some couples will do this to signify that the two of them are forming a new union, separate from that of their families.
i think it’s nice.
When you get married, you get a freebie name change. When you’re filling out your marriage certificate application form at the courthouse, there should be space for you to write in your new name. Just indicate your new name there. Then you will be issued a copy of your marriage certificate with your new name on it, which can be used at the social security agency, DMV, etc. to change your name on all your official docs. Good luck!