Karel Slabbaert (1618 – 1654 in Zierikzee; † before November 6, 1654, in Leiden) was a Dutch painter and draftsman.

His earliest dated work is recorded as 1641 and he got engaged to Cornelia Bouwers of Rotterdam on 8th April 1645.

[1] His works show familiarity with Rembrandt's studio and he was in Amsterdam in 1645 while being a member of the painter's guild in Middelburg the same year.

In his group portrait with soldiers (Mauritshuis Den Haag), he depicted himself in the foreground.

Karel Slabbaert died in Leiden in 1654 and was buried in Middelburg on November 6 of that year.