SJK could refer to:
SJK 171 (Graffiti Artist) (aka Steve the Greek) is one of the earliest New York City graffiti artists of the late 1960s and 1970s. He is generally credited with originating the "swiggly lines", a style of outlining graffiti. His work was the first triple outline, large colorful letters to appear on the 1 Line of the New York City Transit System. This was documented in early 1971. He was also known as "King of the A-Trains", meaning his graffiti dominated the A of the New York City Transit Authority. Later, he was one of the founding members of the United Graffiti Artists.
SJK 171 and Taki 183 the 2 earliest graffiti artist are both of Greek heritage and both from the very small Greek community in Washington Heights. He began writing in 1968 under the name SJK 171 with Mike 171. SJK 171 attended High School of Art and Design along with a number of other early graffiti artists.
It was in early 1971 that SJK 171 was the first to use the "swiggly radiant energy lines" that 10 years later were used by Keith Haring. SJK171 is also credited with pioneering the use of arrows in graffiti writing around this same time.