Interesting! I was also under the impression that Thomas was Harold's Dad's first name, and I've been squinting and trying to figure out what his last name could be. Ah well, at the very least, we can change the 'Unnamed Father' part of Harold's bio in the Family section. 

Side Note: I can make out the words 'TEACHER' and 'EDUCATION' on Thomas' death certificate, which might imply that Harold's dad was a teacher. 

Side Note 2: I can also see 'MARGARET' on the certificate. No idea who she's supposed to be though. 

Dude, 1981 death certificates for Iowa are "first middle last" Look it up! do your due diligence before taking stuff down. If you were more constructive, you wouldn't have looked like an idiot just now by not checking your facts.

And @Potc, Margaret is labeled as his birth mother (Harold's father's birth mother) and that is her maiden name.

Margaret is a first name. Her maiden name would be the last name she was born with. Moreover, there is a blank space below the final heading in the name line. If it's first-middle-last as you claim, the last name space is blank.

Her maiden name, as in the name she had before she was married, was Margaret Chamberlin. The box in which Margaret is located is listed, specifically, as mother's maiden name. So yes you are correct, Margaret is her first name, though it is also a portion of her maiden name. Wow...

There are no missing last names. It doesn't take an entire like to put in a name. Look at the image with a 4k screen. You'll be fine man, it's all good.

Season 5, episode 7, 42 minutes, 45 seconds.

The code for the virus"Dashwood"

Yes, that is the code for the virus. However, Dashwood is not his surname but actually the surname of the main character in his favorite book, Sense and Sensibility. This is also the book where Harold put the engagement ring prior to proposing to Grace.

Now this is just a theory but since many people refer to other people by their last name what if the Machine is doing just that, this is kinda stupid but what if his last name is Admin, the show might have given us his real name all along and just is where we least expected it. It sounds pretty stupid I know and it's just a theory but I want to list all the possibilities.

I think Dashwood is Harolds original surname, since in the same episode as the grace proposal there is also reference to harolds original name from nathan and how he would tell her it and the implications around it also if anyone knows even harold, what his original name was and its not likely something he would ever forget what with him using birds as a way to remember him, also in pic above the D has faded to look like L and A is able to be seen

Its not that harold had a love for birds, its that his father did not. As a baby, although not knowing a thing about birds, his father would talk to him about the birds, because it would calm him. As a result his father learned everything ther was to know about birds, just for harold. &in the season 4 episode 21 where root admits Harold to the “funnyfarm” harold states “I go by many names all derived from species of birds. With this information we can conclude that harolds name will not be harold vogol & will have no relation to birds. He just makes up his names in relation to birds. We can assume his first name is harold though (or atleast his first nickname) after seeing episodes or harold working on old cars with his father as a young boy and he calls him harold (fun fact that shows when harold first started planning to build a computer which would turn out to be the worlds first computer) and in the episode where him and his friends call paris and the police roll up and call over for harold to tell him his father had wandered off from home.