Hugo Waldegrave is the father of Abigail Lockwood (nee. Waldegrave) and the original owner of Waldegrave Manor. Indicated by newspaper articles, Hugo Waldegrave was an esteemed explorer, inventor, and a collector of rare and exotic artifacts. Before his death, he also accrued a large amount of debt for unspecified reasons.
Not much information on Hugo Waldegrave can be gleaned from the games themselves, as he is little more than a background figure in The Room: Old Sins. However, in Fireproof's "Making Of" page for the game, he is said to be "successful", "overbearing", and "pioneering". His obituary paints him as an esteemed and fearless adventurer, but also adds that he leaves behind a house riddled with debt, suggesting a certain amount of recklessness.
If Waldegrave is, as some speculate, the author of the letter in The Room Two - The Crypt, it would also suggest a condescending view towards those of "low breeding and... station" and a sense of intellectual superiority on his part.
Hugo Waldegrave's relationship to his daughter, Abigail Lockwood, is, for the most part, benevolent. It seems that Waldegrave deeply cared for his daughter. He built her the dollhouse in the Attic, which was a staple of her childhood. Abigail was also clearly well-educated, rivaling her father and her husband (Edward Lockwood) in her understanding of mechanics and the arts. Waldegrave trusted Abigail enough to bequeath Waldegrave Manor to her when he died. However, Waldegrave was also financially irresponsible, and left behind a lot of debt for Abigail to take over.
There is some evidence to support that in the years leading up to the events of The Room: Old Sins, Hugo Waldegrave was acquainted with Professor de Montfaucon. The two were possibly scientific colleagues; the beetle collection in Professor de Montfaucon's laboratory resembles a similar collection in the Curiosity Room at Waldegrave Manor, and may have been given to him by Waldegrave. On Montfaucon's recommendation, Waldegrave may have also enlisted the services of Mr. Rigby to obtain a particularly rare Null artifact from a crypt.