High and mighty
Powerful and superior, or arrogantly affecting to be so.
Like those people who ride a high horse, the high and mighty were formerly the powerful and imperious and were glad to be seen to be so. This usage dates from the 15th century and is found in print in Sir Henry Ellis's collection of Letters, which includes a transcript of a letter sent by Robert Waterton to King Henry V, dated 1420:
Ryght excellent hegh and ryght myghty Prynce and most dredde sovereyne Lorde.
These days, letters to the powerful, even to kings, aren't likely to be couched in such 'your cringing, fawning servant, sire' terms. To call someone high and mighty is to imply a criticism of their pomposity.