Ted Miller is a non-canonical character, created for the 2022 miniseries Why Didn't They Ask Evans?, an adaptation of the Agatha Christie novel of the same name. He is the owner of the travelling carnival that comes to Marchbolt. He lets Bobby work at the carnival in exchange for lending the young man his trucks when he does not need them.
Spoiler warning: A spoiler is announced! The following section contains details about the plot of Why Didn't They Ask Evans?.
He is briefly suspected by Frankie to have poisoned Bobby's beer but assures her of his innocence, claiming that having his workers drink while operating heavy machinery would be disastrous; let alone if one slipped them poison. Thus, the person who poisoned Bobby must have used Miller's name as a cover.
Spoilers end here.