Deviants are different random phonetic spellings of the same name. Bowdler seems to be particularly susceptible to this.
Variants are officially recorded spellings or variations of the name that have been consistently continued. There are two main areas that I am aware of where variants on the Bowdler surname have occurred.
In the 15th century a branch of the Bowdler family who lived on the Ridge above Chirbury adopted this as their name. Their pedigree is detailed in the Heralds Visitation of Shropshire. Later in the 17th century their descendants moved back to the Bowdler name and these are the Chirbury line of Bowdlers.
In the 16th century a branch of the Bowdler family who lived around Brompton on the English/Welsh border adopted Gethine as their name. Their pedigree is detailed in the Heralds Visitation of Shropshire.
Brompton is interesting as it is a unique part of England, almost entirely surrounded by Wales. In fact it is not possible to get to Brompton by road without going through Wales.
Later in the 17th century some descendants moved back to the Bowdler name.
In the 17th century, brothers John and Thomas Bowdler from Shropshire emigrated to the Maryland Colony. Quickly, they and their descendants dropped the ‘r’ and became the Bowdle family.
Use of Bowdler as a forename
I have seen many examples of Bowdler being used as a forename. This can either be from taking a mothers maiden name as a forename or, in unconnected families, I believe this comes in reference to the work of Dr Thomas Bowdler.
An example of this is Richard Bowdler Sharpe.