tikzset{vertex style/.style={
    draw=#1,
    thick,
    fill=#1!70,
    text=white,
    ellipse,
    minimum width=2cm,
    minimum height=0.75cm,
    font=small,
    outer sep=3pt, % the usage of this option will be clear later on
  },
}

usetikzlibrary{shapes.geometric}

documentclass[dvipsnames,png,border=10pt,tikz]{standalone}
usepackage{tikz}
usetikzlibrary{shapes.geometric} % required for the ellipse shape
tikzset{vertex style/.style={
    draw=#1,
    thick,
    fill=#1!70,
    text=white,
    ellipse,
    minimum width=2cm,
    minimum height=0.75cm,
    font=small,
    outer sep=3pt,
  },
}
begin{document}
begin{tikzpicture}
node[vertex style=Turquoise] (Rk) {Righteous Kill};
end{tikzpicture}
end{document}

node[options] (a) {text a} ... edge[options] node[options]{text conn} (b);

begin{tikzpicture}[node distance=2.75cm,>=stealth']
node[vertex style=Turquoise] (Rk) {Righteous Kill};

node[vertex style=BurntOrange, above of=Rk,xshift=2em] (BD) {Bryan Dennehy}
 edge [<-,cyan!60!blue] node[text style,above]{starring} (Rk);
end{tikzpicture}

tikzset{
  text style/.style={
    sloped, % the text will be parallel to the connection
    text=black,
    font=footnotesize,
    above
  }
}

begin{tikzpicture}[node distance=2.75cm,>=stealth']
node[vertex style=Turquoise] (Rk) {Righteous Kill};

node[vertex style=BurntOrange, above of=Rk,xshift=2em] (BD) {Bryan Dennehy}
 edge [<-,cyan!60!blue] node[text style]{starring} (Rk);

node[vertex style=BurntOrange, right=1.5cm of Rk,yshift=4ex] (AP) {Al Pacino}
 edge [<-,cyan!60!blue] node[text style]{starring} (Rk);

node[vertex style=red, below right of=Rk,xshift=2em] (JA) {John Avnet}
 edge [<-,cyan!60!blue] node[text style]{director} (Rk);

 node[vertex style=BurntOrange, right=1.5cm of Rk,yshift=-4ex] (RN) {Robert De Niro}
 edge [<-,cyan!60!blue] node[text style]{starring} (Rk);

node[vertex style=MidnightBlue, above right of=Rk,xshift=2em] (Dr) {Drama}
 edge [<-,cyan!60!blue] node[text style]{genre} (Rk);

node[vertex style=Maroon, below of=Rk,xshift=-2em] (Skf) {Serial Killer Films}
 edge [<-,cyan!60!blue] node[text style]{subject} (Rk);

node[vertex style=Maroon, below right of=Skf] (Cf) {Crime Films}
 edge [<-,cyan!60!blue] node[text style]{broader} (Skf);
end{tikzpicture}

begin{pgfonlayer}{background}
draw[Maroon,fill=Maroon,dashed,fill opacity=0.1](Rk.north)
to[closed,curve through={(Rk.north west).. (Rk.west) .. (Rk.south west)
..($(Rk.south west)!0.5!(Skf.north)$) .. (Skf.north     west).. (Skf.west)
.. (Skf.south west) .. ($(Skf.south)!0.75!(Cf.west)$) .. (Cf.west)
.. (Cf.south west) .. (Cf.south) .. (Cf.south east) .. (Cf.east)
.. ($(Cf.north east)!0.65!(Skf.south east)$) .. (Skf.east)
.. (Skf.north east).. ($(Skf.north)!0.35!(Rk.south east)$)
.. (Rk.south east) .. (Rk.east)..(Rk.north east)}](Rk.north);
end{pgfonlayer}

documentclass[dvipsnames,png,border=10pt,tikz]{standalone}
usepackage{tikz}
usetikzlibrary{shapes.geometric} % required for the ellipse shape
usetikzlibrary{arrows, backgrounds, calc, hobby, positioning}

% this avoides some problem with the hobby implementation
% egreg's code from:
% http://www.guitex.org/home/it/forum/5-tex-e-latex/83195-la-libreria-hobby-tikz-non-funziona-piu#83203
ExplSyntaxOn
cs_if_exist:NF prg_stepwise_function:nnnN { cs_gset_eq:NN prg_stepwise_function:nnnN int_step_function:nnnN }
cs_if_exist:NF prg_stepwise_inline:nnnn { cs_gset_eq:NN prg_stepwise_inline:nnnn int_step_inline:nnnn }
ExplSyntaxOff

tikzset{vertex style/.style={
    draw=#1,
    thick,
    fill=#1!70,
    text=white,
    ellipse,
    minimum width=2cm,
    minimum height=0.75cm,
    font=small,
    outer sep=3pt,
  },
  text style/.style={
    sloped,
    text=black,
    font=footnotesize,
    above
  }
}

begin{document}
begin{tikzpicture}[node distance=2.75cm,>=stealth']
node[vertex style=Turquoise] (Rk) {Righteous Kill};

node[vertex style=BurntOrange, above of=Rk,xshift=2em] (BD) {Bryan Dennehy}
 edge [<-,cyan!60!blue] node[text style]{starring} (Rk);

node[vertex style=BurntOrange, right=1.5cm of Rk,yshift=4ex] (AP) {Al Pacino}
 edge [<-,cyan!60!blue] node[text style]{starring} (Rk);

node[vertex style=red, below right of=Rk,xshift=2em] (JA) {John Avnet}
 edge [<-,cyan!60!blue] node[text style]{director} (Rk);

 node[vertex style=BurntOrange, right=1.5cm of Rk,yshift=-4ex] (RN) {Robert De Niro}
 edge [<-,cyan!60!blue] node[text style]{starring} (Rk);

node[vertex style=MidnightBlue, above right of=Rk,xshift=2em] (Dr) {Drama}
 edge [<-,cyan!60!blue] node[text style]{genre} (Rk);

node[vertex style=Maroon, below of=Rk,xshift=-2em] (Skf) {Serial Killer Films}
 edge [<-,cyan!60!blue] node[text style]{subject} (Rk);

node[vertex style=Maroon, below right of=Skf] (Cf) {Crime Films}
 edge [<-,cyan!60!blue] node[text style]{broader} (Skf);

begin{pgfonlayer}{background}
draw[Maroon,fill=Maroon,dashed,fill opacity=0.1](Rk.north)
to[closed,curve through={(Rk.north west).. (Rk.west) .. (Rk.south west)
..($(Rk.south west)!0.5!(Skf.north)$) .. (Skf.north     west).. (Skf.west)
.. (Skf.south west) .. ($(Skf.south)!0.75!(Cf.west)$) .. (Cf.west)
.. (Cf.south west) .. (Cf.south) .. (Cf.south east) .. (Cf.east)
.. ($(Cf.north east)!0.65!(Skf.south east)$) .. (Skf.east)
.. (Skf.north east).. ($(Skf.north)!0.35!(Rk.south east)$)
.. (Rk.south east) .. (Rk.east)..(Rk.north east)}](Rk.north);
end{pgfonlayer}

end{tikzpicture}
end{document}

begin{tikzpicture}[node distance=2.75cm,>=stealth']
node[vertex style=Turquoise] (Rk) {Righteous Kill};

node[vertex style=BurntOrange, above of=Rk,xshift=2em] (BD) {Bryan Dennehy}
 edge [<-,cyan!60!blue] node[text style,above]{starring} (Rk);
end{tikzpicture}