The portrait of Robert Dudley in silver brocade, painted in c.1563 and with his dog by his side, seems to have been copied a lot. One particular set of copies shows Robert wearing red sleeves under a slashed leather jerkin, as well as a red trunk hose. The dog has vanished.
The headgear is the same as in the silver brocade portrait. It again shows the mythical Roman hero, Marcus Curtius, on horseback. Marcus was famed for saving his hometown (Rome) from the abyss by riding into a chasm that had opened in the Forum. It was a fitting allusion to the Master of the Horse, Robert Dudley’s chief office at Elizabeth’s court.
All these paintings have sometimes been attributed to the Flemish painter Steven van der Meulen or his workshop (Steven may be the same Steven as the artist called Steven van Herwijck).

A version that was cut down to head and shoulders of the above portrait now in the National Gallery of Victoria (Australia). The wart is clearly visible.
Further reading:
Elizabeth Goldring, Robert Dudley, Earl of Leicester, and the World of Elizabethan Art: Painting and Patronage at the Court of Elizabeth I, 2014.
Karen Hearn (ed.), Dynasties: Painting in Tudor and Jacobean England 1530–1630, 1995.